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Search: id:A137644
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| A137644 |
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a(n) = Sum_{k=0..n} C(n+k,k)*C(n+k,n-k). |
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+0
1
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| 1, 3, 16, 95, 591, 3780, 24620, 162423, 1081780, 7258053, 48982176, 332140328, 2261099491, 15444137880, 105789736896, 726426836103, 4998885106599, 34464824536500, 238017084356680, 1646234203000485, 11401464090042224
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OFFSET
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0,2
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FORMULA
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a(n)= 3F2( {-n, n+1, n+1}; {1/2, 1})( -(1/4) ) [From Olivier GERARD (olivier.gerard(AT)gmail.com), Apr 23 2009]
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MATHEMATICA
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Table[ HypergeometricPFQ[{-n, 1 + n, 1 + n}, {1/2, 1}, -(1/4)], {n, 0, 20}] [From Olivier GERARD (olivier.gerard(AT)gmail.com), Apr 23 2009]
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PROGRAM
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(PARI) a(n)=sum(k=0, n, binomial(n+k, k)*binomial(n+k, n-k))
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CROSSREFS
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Sequence in context: A067679 A099952 A074555 this_sequence A114174 A006347 A000270
Adjacent sequences: A137641 A137642 A137643 this_sequence A137645 A137646 A137647
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Jan 31 2008
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