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Search: id:A113989
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| 1, 2, 4, 8, 18, 46, 136, 464, 1818, 8122, 41076, 233472, 1480946, 10412590, 80634432, 683674832, 6312152354, 63144706754, 681317547508, 7896054343496, 97919789763074, 1294863406981790, 18200820837825480, 271147632138373600
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OFFSET
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0,2
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FORMULA
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a(n) = A113984(n+1) - 1. a(n) = a(n-2) + A113990(n-2) + 2 for n>=2.
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PROGRAM
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(PARI) {a(n)=local(A, B); A=Mat(1); for(m=2, n+1, B=matrix(m, m); for(i=1, m, for(j=1, i, if(i<3|j==1|j==i, B[i, j]=1, B[i, j]=A[i-1, j-1]+(A^2)[i-2, j-1] ); )); A=B); (A^2)[n+1, 1]}
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CROSSREFS
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Cf. A113988, A113990 (column 1), A113991 (column 2), A113992 (column 3); A113984, A113983, A113993.
Sequence in context: A125809 A000117 A006771 this_sequence A126757 A034766 A099785
Adjacent sequences: A113986 A113987 A113988 this_sequence A113990 A113991 A113992
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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), Nov 12 2005
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