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A100505 Bisection of A001523. 3
1, 2, 8, 27, 79, 209, 512, 1183, 2604, 5504, 11240, 22277, 43003, 81098, 149769, 271404, 483439, 847681, 1464999, 2498258, 4207764, 7005688, 11538936, 18814423, 30387207, 48641220, 77205488, 121567834, 189974638, 294742961, 454164484 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..5000

MAPLE

1, seq(coeff(convert(series(add(-(-1)^k*x^(k*(k+1)/2), k=1..100)/(mul(1-x^k, k=1..100))^2, x, 100), polynom), x, 2*n), n=1..45); (C. Ronaldo)

# second Maple program:

b:= proc(n, i) option remember;

      `if`(i>n, 0, `if`(irem(n, i)=0, 1, 0)+

      add(b(n-i*j, i+1)*(j+1), j=0..n/i))

    end:

a:= n-> `if`(n=0, 1, b(2*n, 1)):

seq(a(n), n=0..60);  # Alois P. Heinz, Mar 26 2014

MATHEMATICA

max = 70; s = 1 + Sum[(-1)^(k+1)*q^(k*(k+1)/2), {k, 1, Sqrt[2 max] // Ceiling}]/QPochhammer[q]^2 + O[q]^max // Normal; Partition[(List @@ s) /. q -> 1, 2][[All, 1]] (* Jean-Fran├žois Alcover, Apr 04 2017 *)

CROSSREFS

Sequence in context: A092071 A289864 A290056 * A102759 A292698 A261056

Adjacent sequences:  A100502 A100503 A100504 * A100506 A100507 A100508

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Nov 24 2004

EXTENSIONS

More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 19 2005

STATUS

approved

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Last modified October 24 10:03 EDT 2021. Contains 348225 sequences. (Running on oeis4.)