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Search: id:A006198
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| A006198 |
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Number of partitions into pairs.
(Formerly M4241)
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+0
2
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| 1, 1, 6, 41, 365, 3984, 51499, 769159, 13031514, 246925295, 5173842311, 118776068256, 2964697094281, 79937923931761, 2315462770608870, 71705109685449689
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OFFSET
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1,3
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REFERENCES
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G. Kreweras and Y. Poupard, Sur les partitions en paires d'un ensemble fini totalement ordonne, Publications de l'Institut de Statistique de l'Universit\'{e} de Paris, 23 (1978), 57-74.
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FORMULA
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a(n) = |A000806(n-1)|+|A000806(n)|. G.f.: Sum_{n>=0} A001147(n)*(x/(1+x)^2)^n. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Jun 27 2007
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CROSSREFS
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Sequence in context: A005011 A009122 A094869 this_sequence A113573 A007130 A075000
Adjacent sequences: A006195 A006196 A006197 this_sequence A006199 A006200 A006201
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KEYWORD
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nonn
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AUTHOR
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njas
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