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A100506 Bisection of A001523. 3
1, 4, 15, 47, 130, 330, 784, 1765, 3804, 7898, 15880, 31048, 59220, 110484, 202070, 362974, 641368, 1116325, 1916184, 3247088, 5436972, 9002752, 14752316, 23938188, 38487496, 61344055, 96974176, 152110204, 236837795, 366177506, 562373990, 858193804, 1301654610 (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

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+1), n=0..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, 1)):

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

MATHEMATICA

b[n_, i_] := b[n, i] = If[i > n, 0, If[Mod[n, i] == 0, 1, 0] + Sum[b[n - i*j, i + 1]*(j + 1), {j, 0, n/i}]];

a[n_] := If[n == 0, 1, b[2*n + 1, 1]];

Table[a[n], {n, 0, 60}] (* Jean-Fran├žois Alcover, Jun 18 2018, after Alois P. Heinz *)

CROSSREFS

Sequence in context: A195688 A111038 A188716 * A173414 A307075 A219903

Adjacent sequences:  A100503 A100504 A100505 * A100507 A100508 A100509

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 June 28 01:48 EDT 2022. Contains 354903 sequences. (Running on oeis4.)