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Search: id:A135882
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| 1, 2, 7, 34, 215, 1698, 16220, 182714, 2378780, 35219202, 585245185, 10797322816, 219163958124, 4856832298391, 116735215192864, 3025759884533190, 84155831914971391, 2500599947944218716, 79072271422935678302
(list; graph; listen)
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OFFSET
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0,2
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LINKS
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Paul D. Hanna, Table of n, a(n) for n = 0..79
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EXAMPLE
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Equals column 1 of triangle P=A135880:
1;
1, 1;
2, 2, 1;
6, 7, 3, 1;
25, 34, 15, 4, 1;
138, 215, 99, 26, 5, 1;
970, 1698, 814, 216, 40, 6, 1; ...
where column k of P^2 equals column 0 of P^(2k+2)
such that column 0 of P^2 equals column 0 of P shift left.
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PROGRAM
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(PARI) {a(n)=local(P=Mat(1), R, PShR); if(n==0, 1, for(i=0, n, PShR=matrix(#P, #P, r, c, if(r>=c, if(r==c, 1, if(c==1, 0, P[r-1, c-1])))); R=P*PShR; R=matrix(#P+1, #P+1, r, c, if(r>=c, if(r<#P+1, R[r, c], if(c==1, (P^2)[ #P, 1], (P^(2*c-1))[r-c+1, 1])))); P=matrix(#R, #R, r, c, if(r>=c, if(r<#R, P[r, c], (R^c)[r-c+1, 1])))); P[n+2, 2])}
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CROSSREFS
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Cf. A135880; other columns: A135881, A135883, A135884.
Sequence in context: A002720 A111539 A074059 this_sequence A143740 A049463 A029894
Adjacent sequences: A135879 A135880 A135881 this_sequence A135883 A135884 A135885
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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), Dec 15 2007
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EXTENSIONS
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Error in entries (false comma) corrected by N. J. A. Sloane (njas(AT)research.att.com), Jan 23 2008
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