A135346 a(0)=1. a(n) = Sum_{k=1..n} a(n-d(k)), where d(k) = A000005(k) (the number of positive divisors of k).

1, 1, 2, 4, 9, 23, 56, 161, 426, 1228, 3422, 10897, 31797, 107868, 334558, 1101073, 3497461, 12456122, 40984747, 153684304, 526066576, 1919047914, 6744790864, 26222498483, 94726314125, 365396084072, 1354096965947, 5175498770227

Offset

0,3

Links

Table of n, a(n) for n=0..27.

Maple

A135346 := proc(n) option remember ; local k ; if n = 0 then 1 ; else add(A135346(n-numtheory[tau](k)), k=1..n) ; fi ; end: seq(A135346(n), n=0..40) ; # R. J. Mathar, Feb 19 2008

Mathematica

a[0]=1; a[n_]:=Sum[a[n-DivisorSigma[0, k]], {k, n}] (* James C. McMahon, Apr 13 2025 *)

Crossrefs

Sequence in context: A159334 A159330 A159331 * A174283 A337516 A340920

Adjacent sequences: A135343 A135344 A135345 * A135347 A135348 A135349

Keyword

nonn

Author

Leroy Quet, Feb 16 2008

Extensions

More terms from R. J. Mathar, Feb 19 2008

Status

approved