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

Author

Antti Karttunen, Nov 24 2018

Keywords

• nonn

Links

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

Crossrefs

Cf. A000005, A049820, A259934.

Cf. also A320002, A320008, A320016.

Programs

Mathematica

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

PARI

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

Formula

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