Buggy python submission (verdict: Time Limit Exceeded):
#!/usr/bin/env python3
# -*- coding: utf-8 -*-


def generate_intervals(n):
    a = 1
    while a == 1 or a <= n // 2:
        yield a
        a = 3 * a + 1


class Sort(object):

    def __init__(self, array, num):
        self.a = array
        self.n = num
        self.cnt = 0
        self.gs = list(reversed(list(generate_intervals(self.n))))
        self.m = len(self.gs)

    def insertionsort(self, g):
        for i in range(g, self.n):
            v = self.a[i]
            j = i - g
            while j >= 0 and self.a[j] > v:
                self.a[j + g] = self.a[j]
                j = j - g
                self.cnt += 1
            self.a[j + g] = v

    def shellsort(self):
        for i in range(0, self.m):
            self.insertionsort(self.gs[i])


def main():
    n = int(input())
    a = [int(input()) for i in range(n)]
    s = Sort(a, n)
    s.shellsort()
    print(s.m)
    print(" ".join(map(str, s.gs)))
    print(s.cnt)
    for i in range(n):
        print(s.a[i])


if __name__ == "__main__":
    main()

Fixed submission:
#!/usr/bin/env python3

def construct_gs(n):
    gs = []
    g = 1
    while g <= n:
        gs.append(g)
        g = 3 * g + 1
    return gs[::-1]


def shell_sort(xs, n):
    global cnt
    cnt = 0
    gs = construct_gs(n)
    m = len(gs)
    def insertion_sort(g):
        global cnt
        for i in range(g, n):
            v = xs[i]
            j = i - g
            while j >= 0 and xs[j] > v:
                xs[j + g] = xs[j]
                j = j - g
                cnt += 1
            xs[j + g] = v
    for g in gs:
        insertion_sort(g)
    return m, gs, cnt, xs


def main():
    n = int(input())
    xs = [int(input()) for _ in range(n)]
    m, gs, cnt, xs = shell_sort(xs, n)
    print(m)
    print(" ".join(map(str, gs)))
    print(cnt)
    for x in xs:
        print(x)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import math


def generate_intervals(n):
    if n > 1:
        l = math.ceil(math.log(2 * n + 1, 3))
        return [(3 ** i - 1) // 2 for i in range(l - 1, 0, -1)]
    else:
        return [1]


class Sort(object):

    def __init__(self, array, num):
        self.a = array
        self.n = num
        self.cnt = 0
        self.gs = generate_intervals(self.n)
        self.m = len(self.gs)

    def insertionsort(self, g):
        for i in range(g, self.n):
            v = self.a[i]
            j = i - g
            while j >= 0 and self.a[j] > v:
                self.a[j + g] = self.a[j]
                j = j - g
                self.cnt += 1
            self.a[j + g] = v

    def shellsort(self):
        for i in range(0, self.m):
            self.insertionsort(self.gs[i])


def main():
    n = int(input())
    a = [int(input()) for i in range(n)]
    s = Sort(a, n)
    s.shellsort()
    print(s.m)
    print(" ".join(map(str, s.gs)))
    print(s.cnt)
    for i in range(n):
        print(s.a[i])


if __name__ == "__main__":
    main()

Fixed submission:
#!/usr/bin/env python3

def construct_gs(n):
    gs = []
    g = 1
    while g <= n:
        gs.append(g)
        g = 3 * g + 1
    return gs[::-1]


def shell_sort(xs, n):
    global cnt
    cnt = 0
    gs = construct_gs(n)
    m = len(gs)
    def insertion_sort(g):
        global cnt
        for i in range(g, n):
            v = xs[i]
            j = i - g
            while j >= 0 and xs[j] > v:
                xs[j + g] = xs[j]
                j = j - g
                cnt += 1
            xs[j + g] = v
    for g in gs:
        insertion_sort(g)
    return m, gs, cnt, xs


def main():
    n = int(input())
    xs = [int(input()) for _ in range(n)]
    m, gs, cnt, xs = shell_sort(xs, n)
    print(m)
    print(" ".join(map(str, gs)))
    print(cnt)
    for x in xs:
        print(x)


if __name__ == '__main__':
    main()