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Search: id:A082397
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| A082397 |
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Number of directed aggregates of height <= 2 with n cells. |
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+0
1
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| 1, 2, 5, 11, 26, 62, 153, 385, 988, 2573, 6786, 18084, 48621, 131718, 359193, 985185, 2715972, 7521567, 20915256, 58373586, 163462815, 459136809, 1293223230, 3651864606, 10336625731, 29321683082, 83344398533, 237344961291
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OFFSET
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1,2
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REFERENCES
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Fouad Ibn-Majdoub-Hassani. Combinatoire de polyominos et des tableaux decales oscillants . These de Doctorat. Laboratoire de Recherche en Informatique, Universite Paris-Sud XI, France.
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FORMULA
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a(n) = Sum_{k=1..n}(-1)^(k+1)*binomial(n+1, k+1)*binomial(k, floor((k-1)/2)). E.g.f.: -exp(x)*int(-BesselI(1, 2*x)+BesselI(2, 2*x), x)-exp(x)*(-BesselI(1, 2*x)+BesselI(2, 2*x)). - Vladeta Jovovic (vladeta(AT)Eunet.yu), Sep 18 2003
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CROSSREFS
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Adjacent sequences: A082394 A082395 A082396 this_sequence A082398 A082399 A082400
Sequence in context: A006138 A124217 A095981 this_sequence A051286 A025245 A079223
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KEYWORD
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nonn
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AUTHOR
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Fouad IBN MAJDOUB HASSANI (fouad.ibnmajdoubhassani(AT)wanadoo.fr), Apr 14 2003
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)Eunet.yu), Sep 18 2003
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