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A113989
Column 0 of triangle A113988, which is the matrix square of A113983: a(n) = [A113983^2](n,0).
11
1, 2, 4, 8, 18, 46, 136, 464, 1818, 8122, 41076, 233472, 1480946, 10412590, 80634432, 683674832, 6312152354, 63144706754, 681317547508, 7896054343496, 97919789763074, 1294863406981790, 18200820837825480, 271147632138373600
OFFSET
0,2
FORMULA
a(n) = A113984(n+1) - 1. a(n) = a(n-2) + A113990(n-2) + 2 for n>=2.
PROG
(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]
CROSSREFS
Cf. A113988, A113990 (column 1), A113991 (column 2), A113992 (column 3); A113984, A113983, A113993.
Sequence in context: A308030 A252653 A006771 * A126757 A369386 A034766
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 12 2005
STATUS
approved