OFFSET
0,2
LINKS
Robert Israel, Table of n, a(n) for n = 0..10000
Raphael Schumacher, The self-counting identity, Fib. Quart., 55 (No. 2 2017), 157-167.
FORMULA
G.f.: (1/(1 - x)^2)*Product_{k>=1} (1 - x^(2*k))^2/(1 - x^(2*k-1))^2. - Ilya Gutkovskiy, May 30 2017
MAPLE
a002024:= [seq(i$i, i=1..10)]:
g002024:= add(a002024[i]*x^(i-1), i=1..nops(a002024)):
g:= expand(g002024^2):
seq(coeff(g, x, i), i=0..degree(g002024)); # Robert Israel, May 30 2017
PROG
(PARI) nn(n)=(sqrtint(n*8)+1)\2;
a(n) = sum(k=1, n, nn(k)*nn(n-k+1)); \\ Michel Marcus, May 30 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved