

A097762


Number of different partitions of the set {1, 2, ..., n} into an odd number of blocks such that each block contains at least 2 elements.


1



0, 1, 1, 1, 1, 16, 106, 491, 1919, 7771, 40261, 264892, 1871728, 12988977, 88413417, 612354549, 4492798353, 35529920764, 299329573882, 2625719242667, 23612697535919, 216981233646783, 2047084700918445, 19952633715109592
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OFFSET

1,6


LINKS

Table of n, a(n) for n=1..24.


FORMULA

Exponential generating function: sinh(exp(x)x1).


EXAMPLE

a(6)=16 since we can partition a set of six labeled elements into one nonsingleton block in 1 way and into three nonsingleton blocks (each necessarily of size 2) in 15 ways; thus a(6)=1+15=16.


MAPLE

seq(coeff(series(sinh(exp(x)x1), x=0, 25), x^i)*i!, i=1..24);


CROSSREFS

Cf. A000296, A097763.
Sequence in context: A146211 A195806 A081588 * A083469 A224160 A224411
Adjacent sequences: A097759 A097760 A097761 * A097763 A097764 A097765


KEYWORD

easy,nonn


AUTHOR

Isabel C. Lugo (izzycat(AT)gmail.com), Aug 23 2004


STATUS

approved



