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Search: id:A120278
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| A120278 |
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Sum[Sum[C(2k,k),{k,1,m}],{m,1,n}], where C(2k,k)=(2k)!/(k!)^2=A000984[k]. |
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1
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| 2, 10, 38, 136, 486, 1760, 6466, 24042, 90238, 341190, 1297574, 4958114, 19019254, 73196994, 282492254, 1092867904, 4236849774, 16455966944, 64020347914, 249431257704, 973100041934, 3800867789884, 14862066265434, 58170868424084
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(2(p-1)) is divisible by p^2 for p=7,13,19,31,37,43,61,67.. A002476 Primes of form 6n + 1.
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FORMULA
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a(n) = Sum[Sum[(2k)!/(k!)^2,{k,1,m}],{m,1,n}].
a(n) = 2 * Sum[ A079309[k], {k,1,n} ] = Sum[ A066796[k], {k,1,n} ]. - Alexander Adamchuk (alex(AT)kolmogorov.com), Sep 01 2006
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MATHEMATICA
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Table[Sum[Sum[(2k)!/(k!)^2, {k, 1, m}], {m, 1, n}], {n, 1, 50}]
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CROSSREFS
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Cf. A000984, A066796, A002476.
Cf. A066796, A079309.
Sequence in context: A110148 A056182 A081956 this_sequence A143960 A122117 A120949
Adjacent sequences: A120275 A120276 A120277 this_sequence A120279 A120280 A120281
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KEYWORD
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nonn
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Jul 04 2006
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