A320009 a(0) = 1; for n > 0, a(n) = A000005(n) * a(n-A000005(n)), where A000005(n) gives the number of divisors of n.

1, 1, 2, 2, 3, 4, 8, 8, 12, 24, 32, 48, 48, 96, 128, 192, 240, 384, 288, 768, 768, 1536, 1152, 3072, 1920, 3456, 4608, 12288, 6912, 24576, 9216, 49152, 27648, 98304, 36864, 196608, 110592, 393216, 147456, 786432, 221184, 1572864, 294912, 3145728, 884736, 4718592, 1179648, 9437184, 1474560, 3538944, 5308416, 37748736, 7077888, 75497472

Offset

0,3

Links

Antti Karttunen, Table of n, a(n) for n = 0..150

Formula

a(0) = 1; for n > 0, a(n) = A000005(n) * a(n-A000005(n)).

Mathematica

Nest[Append[#1, #2 #1[[-#2]] ] & @@ {#, DivisorSigma[0, Length@ #]} &, {1}, 53] (* Michael De Vlieger, Nov 25 2018 *)

Prog

(PARI) A320009(n) = if(0==n, 1, numdiv(n)*A320009(n-numdiv(n)));

Crossrefs

Cf. A000005, A049820, A259934.

Cf. also A320002, A320008, A320016.

Sequence in context: A032252 A112708 A378753 * A147558 A032243 A153922

Adjacent sequences: A320006 A320007 A320008 * A320010 A320011 A320012

Keyword

nonn

Author

Antti Karttunen, Nov 24 2018

Status

approved