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Search: id:A118926
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| A118926 |
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Invariant column vector V under matrix product A104546*V = V: a(n) = Sum_{k=0,[n/2]} A104546(n,k)*a(k). |
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+0
2
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| 1, 2, 7, 28, 125, 598, 3007, 15708, 84585, 466954, 2632167, 15103676, 88012801, 519848442, 3107443803, 18774545752, 114527169657, 704731976138, 4370943547471, 27306560735812, 171728169545661, 1086605771091766
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OFFSET
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0,2
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COMMENT
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Triangle A104546(n,k) = the number of Schroeder paths of length 2n and having k platforms.
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FORMULA
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Self-convolution of A118927.
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PROGRAM
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(PARI) {a(n)=local(G=1+x+x*O(x^n)); if(n==0, 1, for(i=0, n, G=1+x*G+x*G*(G+(y-1)*x/(1-x))); sum(k=0, n\2, a(k)*polcoeff(polcoeff(G+y*O(y^k), n, x), k, y)))}
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CROSSREFS
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Cf. A104546, A118927 (self-convolution square-root).
Sequence in context: A002931 A088702 A112565 this_sequence A127084 A052319 A127783
Adjacent sequences: A118923 A118924 A118925 this_sequence A118927 A118928 A118929
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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), May 06 2006
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