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

1,2

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

Mathematica

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

Prog

(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, ", "))

Crossrefs

Sequence in context: A062832 A089085 A033163 * A039869 A076210 A039014

Adjacent sequences: A228369 A228370 A228371 * A228373 A228374 A228375

Keyword

nonn

Author

Ralf Stephan, Aug 21 2013

Status

approved