A228372 Number of nontrivial divisors in the first n composites.

1, 3, 5, 6, 8, 12, 14, 16, 19, 23, 27, 29, 31, 37, 38, 40, 42, 46, 52, 56, 58, 60, 62, 69, 71, 73, 79, 85, 89, 93, 95, 103, 104, 108, 110, 114, 120, 122, 128, 130, 132, 142, 144, 148, 153, 155, 161, 165, 167, 173, 183, 185, 189, 193, 195, 201, 209, 212, 214, 224, 226

Offset: 1

Author

Ralf Stephan, Aug 21 2013

Keywords

• nonn

Comments

Also, positions where values change in A228363.

Partial sums of A144925.

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..10000

Programs

Mathematica

Accumulate[DivisorSigma[0,#]-2&/@Select[Range[100],CompositeQ]] (* Harvey P. Dale, Nov 10 2017 *)

PARI

L=listcreate();for(n=1,1000,if(!isprime(n),listput(L,n)));co=Vec(L);s=0;for(n=2,100,s=s+numdiv(co[n])-2;print1(s,","))