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A113987
Column 4 of triangle A113983; also a(n) = A113983(n+3,3) + [A113983^2](n+2,3).
4
1, 5, 21, 89, 401, 1969, 10633, 63297, 414857, 2984829, 23485909, 201272257, 1870901681, 18786935025, 203013976769, 2352251860561, 29124175447169, 384114020063301, 5380529664829157, 79829102054901081, 1251315569536252353
OFFSET
0,2
FORMULA
a(n) = [A113983^4](n, 0) + [A113983^5](n-1, 0) = A113995(n) + A113996(n-1).
PROG
(PARI) a(n)=local(A, B); A=Mat(1); for(m=2, n+5, 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[n+5, 5]
CROSSREFS
Cf. A113983, A113984 (column 1), A113985 (column 2), A113986 (column 3).
Sequence in context: A015448 A273796 A035011 * A188707 A360580 A333538
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 12 2005
STATUS
approved