A058699 a(n) = p(p(n)), p = partition numbers A000041.

1, 1, 2, 3, 7, 15, 56, 176, 1002, 5604, 53174, 526823, 10619863, 214481126, 9035836076, 476715857290, 51820051838712, 7479565078510584, 2645418340688763701, 1318520401612270233223, 1774758704783877366657989, 4025091510519029370421431033

Offset: 0

Author

N. J. A. Sloane, Dec 31 2000

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..50

Crossrefs

Cf. A000009, A000041, A284908, A284909, A284910.

Programs

Maple

a:= n-> (combinat[numbpart]@@2)(n):
seq(a(n), n=0..22);  # Alois P. Heinz, Apr 05 2017

Mathematica

Table[Nest[PartitionsP, n, 2], {n, 0, 20}] (* Michael De Vlieger, Apr 25 2016 *)

PARI

a(n) = numbpart(numbpart(n)); \\ Michel Marcus, Apr 25 2016

Formula

a(n) = A000041(A000041(n)). - Omar E. Pol, Apr 25 2016