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Search: id:A105558
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| A105558 |
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Central terms in even-indexed rows of triangle A105556, and thus equals the n-th row sum of the n-th matrix power of the Narayana triangle A001263. |
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1
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| 1, 2, 12, 148, 3105, 99156, 4481449, 272312216, 21414443481, 2116193061340, 256712977920256, 37506637787774112, 6496315164318118165, 1316230822119433518312, 308426950979497974254310
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OFFSET
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0,2
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COMMENT
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Each term a(n) is divisible by (n+1) for all n>=0.
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EXAMPLE
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Terms a(n) divided by (n+1) begin:
1,1,4,37,621,16526,640207,34039027,2379382609,211619306134,...
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PROGRAM
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(PARI) {a(n)=local(N=matrix(n+1, n+1, m, j, if(m>=j, binomial(m-1, j-1)*binomial(m, j-1)/j))); sum(j=0, n, (N^n)[n+1, j+1])}
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CROSSREFS
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Cf. A001263, A105556.
Adjacent sequences: A105555 A105556 A105557 this_sequence A105559 A105560 A105561
Sequence in context: A010790 A086928 A001927 this_sequence A126777 A126345 A000795
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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), Apr 14 2005
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