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Search: id:A109155
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| 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
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0,2
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COMMENT
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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.
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PROGRAM
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(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)[r-1, c]))))); return(M[n+3, 3])}
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CROSSREFS
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Cf. A109152 (triangle), A109153 (column 0), A109154 (column 1), A109156 (row sums).
Sequence in context: A054718 A132390 A152761 this_sequence A081072 A000717 A076020
Adjacent sequences: A109152 A109153 A109154 this_sequence A109156 A109157 A109158
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Jun 20 2005
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