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A113991
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Column 2 of triangle A113988, which is the matrix square of A113983: a(n) = [A113983^2](n+2,2).
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4
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1, 6, 26, 108, 468, 2194, 11294, 64152, 402072, 2773606, 20981626, 173331444, 1557019148, 15144482402, 158854971230, 1790084290832, 21593325563600, 277903063486054, 3804108755321242, 55227351469322460, 848094468268734116
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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PROG
| (PARI) {a(n)=local(A, B); A=Mat(1); for(m=2, n+3, 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+3, 3]}
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CROSSREFS
| Cf. A113988, A113989 (column 0), A113990 (column 1), A113992 (column 3).
Sequence in context: A027996 A020989 A079675 * A145374 A124465 A164549
Adjacent sequences: A113988 A113989 A113990 * A113992 A113993 A113994
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KEYWORD
| nonn
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AUTHOR
| Paul D. Hanna (pauldhanna(AT)juno.com), Nov 12 2005
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