A103416 a(n) = n - ceiling(sqrt(prime(n))).

-1, 0, 0, 1, 1, 2, 2, 3, 4, 4, 5, 5, 6, 7, 8, 8, 9, 10, 10, 11, 12, 13, 13, 14, 15, 15, 16, 17, 18, 19, 19, 20, 21, 22, 22, 23, 24, 25, 26, 26, 27, 28, 29, 30, 30, 31, 32, 33, 33, 34, 35, 36, 37, 38, 38, 39, 40, 41, 42, 43, 44, 44, 45, 46, 47, 48, 48, 49, 50, 51, 52, 53, 53, 54, 55

Offset: 0

Author

Giovanni Teofilatto, Mar 21 2005

Keywords

• sign

Crossrefs

Cf. A104103.

Programs

Mathematica

Table[n - Ceiling[ Sqrt[ Prime[ n]]], {n, 75}] (* Robert G. Wilson v, Mar 24 2005 *)

Python

from math import isqrt
from sympy import prime
def A103416(n): return n-isqrt(prime(n+1)) # Chai Wah Wu, Jul 29 2022

Formula

a(n) = n - A104103(n). - Michel Marcus, Jul 30 2022

Extensions

More terms from Robert G. Wilson v, Mar 24 2005