OFFSET
0,5
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..10000
FORMULA
G.f.: Sum_{k>=0} x^(k^2)/(1-x)^k.
EXAMPLE
a(7)=5 because we have 7, 4+3, 3+4, 5+2 and 2+5.
MAPLE
G:=sum(x^(k^2)/(1-x)^k, k=0..20): Gser:=series(G, x=0, 56): seq( coeff( Gser, x^n), n=0..54); # Emeric Deutsch
MATHEMATICA
nmax = 60; Flatten[{1, Rest[CoefficientList[Series[Sum[x^(k^2)/(1-x)^k, {k, 1, Sqrt[nmax]}], {x, 0, nmax}], x]]}] (* Vaclav Kotesovec, Nov 11 2018 *)
PROG
(PARI) my(N=66, x='x+O('x^N)); Vec(sum(n=1, N, x^(n*n)*(1)/(1-x)^n)) \\ Joerg Arndt, Jan 23 2024
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, Sep 27 2004
EXTENSIONS
More terms from Emeric Deutsch, Mar 29 2005
Prepended a(0)=1 to match g.f., Joerg Arndt, Apr 22 2014
STATUS
approved