Buggy python submission (verdict: Runtime Error):
import numpy as np
n = int(input())

if n == 1:
    print(1)
else:
    res_v = np.zeros(n + 1, dtype='int64')
    res_v_cumsum = np.zeros(n + 1, dtype='int64')
    res_v[0] = 0
    res_v[1] = 1
    res_v[2] = 1
    res_v_cumsum[0] = 0
    res_v_cumsum[1] = 1
    res_v_cumsum[2] = 2

    M = 1000000007

    for k in range(3, n):
        res_v[k] = (1 + res_v_cumsum[k-1] - res_v[k-2]) % M
        res_v_cumsum[k] = (res_v_cumsum[k-1] + res_v[k]) % M

    print((((res_v_cumsum[n-2] * (((n-1) * (n-1)) % M)) % M) + ((res_v_cumsum[n-1] * (n-1)) % M) + n + (n-1)*(n-1)%M) % M)

Fixed submission:
n = int(input())

if n == 1:
    print(1)
else:
    res_v = [0]*(n + 1)
    res_v_cumsum = [0]*(n + 1)
    res_v[0] = 0
    res_v[1] = 1
    res_v[2] = 1
    res_v_cumsum[0] = 0
    res_v_cumsum[1] = 1
    res_v_cumsum[2] = 2

    M = 1000000007

    for k in range(3, n):
        res_v[k] = (1 + res_v_cumsum[k-1] - res_v[k-2]) % M
        res_v_cumsum[k] = (res_v_cumsum[k-1] + res_v[k]) % M
    #print(res_v)
    print((((res_v_cumsum[n-2] * (((n-1) * (n-1)) % M)) % M) + ((res_v_cumsum[n-1] * (n-1)) % M) + n + (n-1)*(n-1)%M) % M)

Buggy python submission (verdict: Time Limit Exceeded):
import numpy as np
n = int(input())

if n == 1:
    print(1)
else:
    res_v = np.zeros(n + 1, dtype='int64')
    res_v_cumsum = np.zeros(n + 1, dtype='int64')
    res_v[0] = 0
    res_v[1] = 1
    res_v[2] = 1
    res_v_cumsum[0] = 0
    res_v_cumsum[1] = 1
    res_v_cumsum[2] = 2

    M = 1000000007

    for k in range(3, n):
        res_v[k] = (1 + res_v_cumsum[k-1] - res_v[k-2]) % M
        res_v_cumsum[k] = (res_v_cumsum[k-1] + res_v[k]) % M

    print((((res_v_cumsum[n-2] * (((n-1) * (n-1)) % M)) % M) + ((res_v_cumsum[n-1] * (n-1)) % M) + n + (n-1)*(n-1)%M) % M)

Fixed submission:
n = int(input())

if n == 1:
    print(1)
else:
    res_v = [0]*(n + 1)
    res_v_cumsum = [0]*(n + 1)
    res_v[0] = 0
    res_v[1] = 1
    res_v[2] = 1
    res_v_cumsum[0] = 0
    res_v_cumsum[1] = 1
    res_v_cumsum[2] = 2

    M = 1000000007

    for k in range(3, n):
        res_v[k] = (1 + res_v_cumsum[k-1] - res_v[k-2]) % M
        res_v_cumsum[k] = (res_v_cumsum[k-1] + res_v[k]) % M
    #print(res_v)
    print((((res_v_cumsum[n-2] * (((n-1) * (n-1)) % M)) % M) + ((res_v_cumsum[n-1] * (n-1)) % M) + n + (n-1)*(n-1)%M) % M)

Buggy python submission (verdict: Runtime Error):
import numpy as np
n = int(input())

res_v = np.zeros(n + 1, dtype='int64')
res_v_cumsum = np.zeros(n + 1, dtype='int64')
res_v[0] = 0
res_v[1] = 1
res_v[2] = 1
res_v_cumsum[0] = 0
res_v_cumsum[1] = 1
res_v_cumsum[2] = 2

M = 1000000007

for k in range(3, n):
    res_v[k] = (1 + res_v_cumsum[k-1] - res_v[k-2]) % M
    res_v_cumsum[k] = (res_v_cumsum[k-1] + res_v[k]) % M

print((((res_v_cumsum[n-2] * (((n-1) * (n-1)) % M)) % M) + ((res_v_cumsum[n-1] * (n-1)) % M) + n + (n-1)*(n-1)%M) % M)

Fixed submission:
n = int(input())

if n == 1:
    print(1)
else:
    res_v = [0]*(n + 1)
    res_v_cumsum = [0]*(n + 1)
    res_v[0] = 0
    res_v[1] = 1
    res_v[2] = 1
    res_v_cumsum[0] = 0
    res_v_cumsum[1] = 1
    res_v_cumsum[2] = 2

    M = 1000000007

    for k in range(3, n):
        res_v[k] = (1 + res_v_cumsum[k-1] - res_v[k-2]) % M
        res_v_cumsum[k] = (res_v_cumsum[k-1] + res_v[k]) % M
    #print(res_v)
    print((((res_v_cumsum[n-2] * (((n-1) * (n-1)) % M)) % M) + ((res_v_cumsum[n-1] * (n-1)) % M) + n + (n-1)*(n-1)%M) % M)

Buggy python submission (verdict: Runtime Error):
n = int(input())

res_v = np.zeros(n + 1, dtype='int64')
res_v_cumsum = np.zeros(n + 1, dtype='int64')
res_v[0] = 0
res_v[1] = 1
res_v[2] = 1
res_v_cumsum[0] = 0
res_v_cumsum[1] = 1
res_v_cumsum[2] = 2

M = 1000000007

for k in range(3, n):
    res_v[k] = (1 + res_v_cumsum[k-1] - res_v[k-2]) % M
    res_v_cumsum[k] = (res_v_cumsum[k-1] + res_v[k]) % M

print((((res_v_cumsum[n-2] * (((n-1) * (n-1)) % M)) % M) + ((res_v_cumsum[n-1] * (n-1)) % M) + n + (n-1)*(n-1)%M) % M)

Fixed submission:
n = int(input())

if n == 1:
    print(1)
else:
    res_v = [0]*(n + 1)
    res_v_cumsum = [0]*(n + 1)
    res_v[0] = 0
    res_v[1] = 1
    res_v[2] = 1
    res_v_cumsum[0] = 0
    res_v_cumsum[1] = 1
    res_v_cumsum[2] = 2

    M = 1000000007

    for k in range(3, n):
        res_v[k] = (1 + res_v_cumsum[k-1] - res_v[k-2]) % M
        res_v_cumsum[k] = (res_v_cumsum[k-1] + res_v[k]) % M
    #print(res_v)
    print((((res_v_cumsum[n-2] * (((n-1) * (n-1)) % M)) % M) + ((res_v_cumsum[n-1] * (n-1)) % M) + n + (n-1)*(n-1)%M) % M)