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A088009
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Number of "sets of odd lists", cf. A000262.
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7
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1, 1, 7, 25, 181, 1201, 10291, 97777, 1013545, 12202561, 151573951, 2173233481, 31758579997, 524057015665, 8838296029291, 164416415570401, 3145357419120721, 65057767274601217, 1391243470549894135, 31671795881695430521
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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FORMULA
| E.g.f.: exp(x/(1-x^2)).
a(n) = n!*sum(k=1..n, A168561(n-1,k-1)/k!). [From Vladimir Kruchinin, Mar 07 2011].
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MAPLE
| T:= (n, k)-> `if` (n-k mod 2 = 0, binomial((n+k)/2, k), 0):
a:= n-> n! * add (T(n-1, k-1)/k!, k=0..n):
seq (a(n), n=0..40); # Alois P. Heinz, Mar 07 2011
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PROG
| (Pari)
x='x+O('x^33); /* that many terms */
Vec(serlaplace(exp(x/(1-x^2)))) /* show terms, and a(0)=1 */
/* Joerg Arndt, Mar 09 2011 */
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CROSSREFS
| Cf. A052845, A088026.
Sequence in context: A082651 A151491 A191237 * A197913 A197651 A198022
Adjacent sequences: A088006 A088007 A088008 * A088010 A088011 A088012
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KEYWORD
| nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Nov 02 2003
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