Original: 2, 11, 17, 29, 41, ...  respectively, where (x) is the prime-counting function, that is, the number of primes less than or equal to x. The converse of this result is the definition of Ramanujan primes, and the numbers 2, 11, 17, 29, 41 are first few such primes.
Simplified: 2, 11, 17, 29, 41, ...  where (x) is the prime counting function. The prime counting function is the number of primes less than or equal to x. The numbers 2, 11, 17, 29, 41 are first few Ramanujan primes.