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A120452
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Number of partitions of n-1 boys and one girl with no couple.
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0
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1, 1, 3, 5, 9, 14, 23, 34, 52, 75, 109, 153, 216, 296, 407, 549, 739, 981, 1300, 1702, 2224, 2879, 3716, 4761, 6083, 7721, 9774, 12306, 15450, 19307, 24064, 29867, 36978, 45614, 56130, 68846, 84250, 102793, 125148, 151955, 184123, 222553, 268482
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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FORMULA
| a(n) = A000070(n-2) + A002865(n-1). - Fung Cheok Yin (cheokyin_restart(AT)yahoo.com.hk), Aug 15 2006
a(n) = A000070(n-1) - A000041(n-2) = A000070(n-3) + A000041(n-1). - Max Alekseyev (maxale(AT)gmail.com), Aug 23 2006
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EXAMPLE
| n=5:
If partitions have no pair "o*", then a(5)=9 ("o" means a boy, "*" means a girl): {o, o, o, o, *}, {o, o, *, oo}, {*, oo, oo}, {o, *, ooo}, {o, o, oo*}, {oo, oo*}, {*, oooo}, {o, ooo*}, {oooo*}.
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CROSSREFS
| Cf. A000070.
Sequence in context: A053618 A032801 A033818 * A144116 A061556 A053993
Adjacent sequences: A120449 A120450 A120451 * A120453 A120454 A120455
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KEYWORD
| nonn,easy
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AUTHOR
| Yasutoshi Kohmoto zbi74583(AT)boat.zero.ad.jp, Jul 20 2006
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EXTENSIONS
| More terms from Fung Cheok Yin (cheokyin_restart(AT)yahoo.com.hk), Aug 15 2006
More terms from Max Alekseyev (maxale(AT)gmail.com), Aug 23 2006
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