A126613 a(1)=1. a(n) = a(n-1) + (number of terms, from among terms a(1) through a(n-1), which are powers of primes {including 1}).

1, 2, 4, 7, 11, 16, 22, 28, 34, 40, 46, 52, 58, 64, 71, 79, 88, 97, 107, 118, 129, 140, 151, 163, 176, 189, 202, 215, 228, 241, 255, 269, 284, 299, 314, 329, 344, 359, 375, 391, 407, 423, 439, 456, 473, 490, 507, 524, 541, 559, 577, 596, 615, 634, 653, 673, 694

Offset

1,2

Links

Table of n, a(n) for n=1..57.

Example

There are 7 prime powers (1,2,4,7,11,16,64) among the first 14 terms of the sequence. So a(15) = a(14) + 7 = 71.

Mathematica

a = {1}; Do[AppendTo[a, a[[ -1]] + 1 + Length[Select[a, Length[FactorInteger[ # ]] == 1 &]]], {60}]; a (* Stefan Steinerberger, Oct 16 2007 *)

Crossrefs

Cf. A131073.

Sequence in context: A061784 A005311 A296202 * A024224 A025727 A319159

Adjacent sequences: A126610 A126611 A126612 * A126614 A126615 A126616

Keyword

nonn

Author

Leroy Quet, Jun 13 2007

Extensions

More terms from Stefan Steinerberger, Oct 16 2007

Status

approved