A046667 a(n) = A046666(n)/2.

0, 0, 1, 0, 2, 0, 3, 3, 4, 0, 5, 0, 6, 6, 7, 0, 8, 0, 9, 9, 10, 0, 11, 10, 12, 12, 13, 0, 14, 0, 15, 15, 16, 15, 17, 0, 18, 18, 19, 0, 20, 0, 21, 21, 22, 0, 23, 21, 24, 24, 25, 0, 26, 25, 27, 27, 28, 0, 29, 0, 30, 30, 31, 30, 32, 0, 33, 33, 34, 0, 35, 0, 36, 36

Offset: 2

Author

N. J. A. Sloane

Keywords

• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 2..1000

Crossrefs

Cf. A046666.

Programs

Mathematica

Table[(1/2)(n - First@(First/@FactorInteger[n])), {n, 2, 100}] (* Vincenzo Librandi, Apr 08 2020 *)

PARI

a(n)={if(n==1, 0, my(f=factor(n)[,1]); (n-f[1])/2)} \\ Andrew Howroyd, Mar 07 2020