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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)
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OFFSET
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0,2
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LINKS
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Alois P. Heinz, Table of n, a(n) for n = 0..5000
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MAPLE
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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
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MATHEMATICA
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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-François Alcover, Jun 18 2018, after Alois P. Heinz *)
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CROSSREFS
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Sequence in context: A195688 A111038 A188716 * A173414 A307075 A219903
Adjacent sequences: A100503 A100504 A100505 * A100507 A100508 A100509
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane, Nov 24 2004
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EXTENSIONS
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More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 19 2005
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STATUS
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approved
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