A144489 Partial sums of A087624.

0, 0, 0, 1, 1, 3, 3, 4, 5, 7, 7, 9, 9, 11, 13, 14, 14, 16, 16, 18, 20, 22, 22, 24, 25, 27, 28, 30, 30, 33, 33, 34, 36, 38, 40, 42, 42, 44, 46, 48, 48, 51, 51, 53, 55, 57, 57, 59, 60, 62, 64, 66, 66, 68, 70, 72, 74, 76, 76, 79, 79, 81, 83, 84, 86, 89, 89, 91, 93, 96, 96, 98, 98, 100, 102

Offset: 1

Author

N. J. A. Sloane, Dec 11 2008

Keywords

• nonn

Comments

Number of pairs (p,q) with 1 < p < q <= n, p|q and p prime. - Wesley Ivan Hurt, Oct 30 2022

Crossrefs

Cf. A002541, A087624.

Programs

Mathematica

Accumulate[Array[If[PrimeQ[#],0,PrimeNu[#]]&,110]] (* Harvey P. Dale, Jul 19 2019 *)

PARI

a(n) = sum(k=1, n, if (!isprime(k), omega(k))); \\ Michel Marcus, Nov 06 2022