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A109156 Row sums of triangle A109152. 4
1, 2, 5, 14, 47, 188, 867, 4460, 25025, 150890, 967825, 6554482, 46600855, 346228012, 2677951311, 21495038944, 178565654041, 1531692226714, 13538763090277, 123096619532030, 1149440819867767, 11007471611129700 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

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

LINKS

Table of n, a(n) for n=0..21.

PROG

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

CROSSREFS

Cf. A109152 (triangle), A109153 (column 0), A109154 (column 1), A109155 (column 2).

Sequence in context: A317784 A096402 A007268 * A143918 A129867 A119841

Adjacent sequences:  A109153 A109154 A109155 * A109157 A109158 A109159

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jun 20 2005

STATUS

approved

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Last modified February 23 08:18 EST 2019. Contains 320420 sequences. (Running on oeis4.)