OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..10000
FORMULA
G.f.: 1/(Product_{i>=1} (1-x^(i!)))/(1-x).
G.f.: 1/(1-x) + Sum_{n>0} x^(n!) / Product_{k=0..n} (1 - x^(k!)). - Seiichi Manyama, Oct 12 2019
EXAMPLE
a(3) = 6 because we can write 3 = 2!+1! = 2!+0! = 1!+1!+1! = 0!+0!+0! = 1!+1!+0! = 1!+0!+0!.
G.f.: 1/(1-x) + x/(1-x)^2 + x^2/((1-x)^2*(1-x^2)) + x^6/((1-x)^2*(1-x^2)*(1-x^6)) + ... . - Seiichi Manyama, Oct 12 2019
MATHEMATICA
nn=51; CoefficientList[Series[Product[1/(1-x^(i!)), {i, 0, 10}], {x, 0, nn}], x] (* Geoffrey Critzer, Sep 29 2013 *)
Table[Length@IntegerPartitions[n, All, Factorial[Range[0, 6]]], {n, 0, 51}] (* Robert Price, Jun 04 2020 *)
PROG
(PARI) N=66; x='x+O('x^N); m=1; while(N>=m!, m++); Vec(1/prod(k=0, m-1, 1-x^k!)) \\ Seiichi Manyama, Oct 13 2019
(PARI) N=66; x='x+O('x^N); m=1; while(N>=m!, m++); Vec(1/(1-x)+sum(i=1, m-1, x^i!/prod(j=0, i, 1-x^j!))) \\ Seiichi Manyama, Oct 13 2019
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Naohiro Nomoto, Oct 30 2001
EXTENSIONS
More terms from Vladeta Jovovic and Don Reble, Nov 02 2001
STATUS
approved