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Search: id:A121417
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| 1, 2, 9, 69, 769, 11346, 208914, 4613976, 118840164, 3496297632, 115638728395, 4246267163601, 171369282105510, 7538270885559264, 358926669220446804, 18389706733665138450, 1008742283718489346668, 58981158542987625464424
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OFFSET
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0,2
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COMMENT
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Also column 1 of square array A136737.
A121416 is the matrix square of triangle A121412; row n of triangle T=A121412 equals row (n-1) of T^(n+1) with an appended '1'.
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PROGRAM
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(PARI) {a(n)=local(A=Mat(1), B); for(m=1, n+2, B=matrix(m, m); for(i=1, m, for(j=1, i, if(j==i, B[i, j]=1, B[i, j]=(A^i)[i-1, j]); )); A=B); return((A^2)[n+2, 2])}
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CROSSREFS
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Cf. A121416 (triangle); other columns: A121418, A121419.
Cf. A136737; A121413, A121422; A121427, A136741.
Sequence in context: A120980 A020563 A006849 this_sequence A167016 A108522 A014500
Adjacent sequences: A121414 A121415 A121416 this_sequence A121418 A121419 A121420
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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), Aug 22 2006
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EXTENSIONS
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Edited by N. J. A. Sloane (njas(AT)research.att.com), Oct 30 2008 at the suggestion of R. J. Mathar
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