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Search: id:A011966
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| A011966 |
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Third differences of Bell numbers. |
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+0
3
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| 1, 5, 20, 87, 409, 2066, 11155, 64077, 389946, 2504665, 16923381, 119928232, 888980293, 6876320041, 55382419676, 463539664643, 4024626253845, 36189297168874, 336513491259647, 3231446022478129, 32004743929977258
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Number of partitions of n+4 with at least one singleton and with the smallest element in a singleton equal to 4. Alternatively, number of partitions of n+4 with at least one singleton and with the largest element in a singleton equal to n+1. - Olivier GERARD (olivier.gerard(AT)gmail.com), Oct 29 2007
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REFERENCES
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Olivier Gerard and Karol A. Penson, A budget of set partition statistics, in preparation.
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MAPLE
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a:= n-> sum ((-1)^(k+1) *binomial(3, k) *combinat['bell'](n+k), k=0..3): seq (a(n), n=0..20); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Sep 05 2008]
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CROSSREFS
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Cf. A000110.
Cf. A005493, A011965.
Sequence in context: A145932 A026661 A099014 this_sequence A017966 A002745 A020046
Adjacent sequences: A011963 A011964 A011965 this_sequence A011967 A011968 A011969
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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