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Search: id:A121421
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| 1, 3, 12, 76, 711, 9054, 147471, 2938176, 69328365, 1891371807, 58575539361, 2030011517685, 77827890696820, 3270046577551695, 149407542447596319, 7374639622066056408, 391044078030333899385, 22168014954558449549349
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OFFSET
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0,2
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COMMENT
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Also column 2 of square array A136733.
A121420 is the matrix cube 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+1, 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^3)[n+1, 1])}
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CROSSREFS
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Cf. A121420 (triangle); other columns: A121422, A121423.
Cf. A136733; A101483, A121418; A121425.
Sequence in context: A120591 A032114 A060946 this_sequence A108043 A058561 A058107
Adjacent sequences: A121418 A121419 A121420 this_sequence A121422 A121423 A121424
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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 23 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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