A065864 - OEIS

A065864

Remainder when n is divided by the number of nonprimes not exceeding n.

0, 0, 0, 0, 1, 0, 1, 0, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 17, 17, 18, 18, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 21, 21, 21, 21, 21, 21

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,9

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = n mod (n-pi(n)) = n mod (n-A000720(n)) = n mod A062298(n).

EXAMPLE

For n=100, pi(100)=25, so a(100) = 100 mod (100-25) = 25.

MATHEMATICA

Table[Mod[n, n - PrimePi@ n], {n, 78}] (* or *)

Table[Mod[n, Count[Range@ n, k_ /; ! PrimeQ@ k]], {n, 78}] (* Michael De Vlieger, Jan 01 2017 *)