OFFSET
0,8
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..10000 (first 1001 terms from Andrew Howroyd)
N. J. A. Sloane, Transforms
FORMULA
Weigh Transform of characteristic function of A000069.
MAPLE
g:= proc(n) option remember; is(add(i, i=Bits[Split](n))::odd) end:
b:= proc(n, i) option remember; `if`(i*(i+1)/2<n, 0, `if`(n=0, 1,
b(n, i-1)+`if`(g(i), b(n-i, min(n-i, i-1)), 0)))
end:
a:= n-> b(n$2):
seq(a(n), n=0..100); # Alois P. Heinz, Sep 08 2019
MATHEMATICA
seq[n_] := Product[If[OddQ[Total[DigitCount[Abs[k], 2, 1]]], 1 + x^k, 1], {k, 1, n}] + O[x]^n // CoefficientList[#, x]&;
seq[100] (* Jean-François Alcover, Sep 08 2019 *)
PROG
(PARI) seq(n)={Vec(prod(k=1, n, if(hammingweight(k)%2==1, 1+x^k, 1) + O(x*x^n)))} \\ Andrew Howroyd, Jun 22 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Christian G. Bower, Feb 17 2006
STATUS
approved