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Search: id:A072374
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| A072374 |
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a(1) = 1; a(n) = 1 + Sum_{i=1..n} Product_{j=i..2*i-1} (n-j). |
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+0
7
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| 1, 2, 3, 6, 11, 24, 51, 122, 291, 756, 1979, 5526, 15627, 46496, 140451, 442194, 1414931, 4687212, 15785451, 54764846, 193129659, 698978136, 2570480147, 9672977706, 36967490691, 144232455524, 571177352091, 2304843053382, 9434493132011, 39289892366736
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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A122852 is another version of the same sequence. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 18 2008
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FORMULA
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The sequence 1, 1, 2, 3, .. has a(n)=sum{k=0..floor(n/2), C(n-k, k)k!} (diagonal sums of permutation triangle A008279). - Paul Barry (pbarry(AT)wit.ie), May 12 2004
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CROSSREFS
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Adjacent sequences: A072371 A072372 A072373 this_sequence A072375 A072376 A072377
Sequence in context: A047750 A072187 A122852 this_sequence A107113 A032256 A051603
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KEYWORD
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nonn
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AUTHOR
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njas, Jul 19 2002
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