A004797 Convolution of A002024 with itself.

1, 4, 8, 14, 22, 30, 41, 54, 67, 82, 99, 118, 138, 160, 182, 206, 234, 262, 292, 322, 353, 388, 425, 462, 501, 542, 583, 626, 671, 718, 766, 818, 870, 922, 976, 1030, 1088, 1148, 1210, 1274, 1338, 1402, 1469, 1538, 1607, 1678, 1753, 1828, 1905, 1984, 2063

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

Cf. A002024.

Sequence in context: A312706 A312707 A337232 * A053459 A024398 A054347

Adjacent sequences: A004794 A004795 A004796 * A004798 A004799 A004800

Keyword

nonn

Author

N. J. A. Sloane

Status

approved