

A109155


Column 2 of triangle A109152.


6



1, 3, 6, 24, 102, 516, 2814, 16752, 106026, 712260, 5027190, 37158600, 286141638, 2289018708, 18961164774, 162271001760, 1431533922642, 12994777356228, 121174578691398, 1159065402957240, 11357543381281638, 113876839666712676
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OFFSET

0,2


COMMENTS

Triangular matrix T=A109152 satisfies: T(n,k) = [T^2](n1,k) for n>k+1>=1, with T(n,n) = 1 and T(n+1,n) = n+1 for n>=0.


LINKS



PROG

(PARI) {a(n)=local(M=matrix(n+3, n+3)); M=M^0; for(i=1, n, M=matrix(n+3, n+3, r, c, if(r>=c, if(r==c, 1, if(r==c+1, c, (M^2)[r1, c]))))); return(M[n+3, 3])}


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



