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Search: id:A104447
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| 1, 2, 5, 13, 39, 139, 587, 2897, 16462, 106301, 771313, 6228073, 55494336, 541651873, 5753940704, 66147591142, 818802488476, 10864622564915, 153914784829775, 2319599022540318, 37068215129072522, 626279667948552452
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OFFSET
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0,2
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COMMENT
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A104446 equals the square of triangular matrix A104445, read by rows, where X=A104445 satisfies: SHIFT_LEFT_UP(X) = X^2 - X + I.
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FORMULA
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a(n) = A091352(n-1) + A091353(n-1).
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PROGRAM
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(PARI) {a(n)=local(A=Mat(1), B); for(m=1, n+1, B=A^2-A+A^0; A=matrix(m+1, m+1); for(i=1, m+1, for(j=1, i, if(i<2|j==i, A[i, j]=1, if(j==1, A[i, j]=1, A[i, j]=B[i-1, j-1]))))); return((A^2)[n+2, 2])}
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CROSSREFS
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Cf. A104446, A091352, A091353.
Sequence in context: A022894 A149861 A148305 this_sequence A127986 A133448 A149862
Adjacent sequences: A104444 A104445 A104446 this_sequence A104448 A104449 A104450
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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), Mar 08 2005
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