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Search: id:A118397
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| A118397 |
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Eigenvector of triangle A105070, where A105070(n,k) = 2^k*C(n+1,2*k+1) for 0<=k<=[n/2], n>=0. |
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3
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| 1, 2, 7, 20, 73, 254, 895, 3080, 10801, 38426, 138775, 504284, 1838137, 6705494, 24464719, 89204624, 324981985, 1183034546, 4305313447, 15672486692, 57100841641, 208309692974, 761141694367, 2785955603096, 10215141094417
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Self-convolution of A118398, which is also an eigenvector of the triangle defined by T(n,k) = 2^k*C(n,2*k).
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FORMULA
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Eigenvector: a(n) = Sum_{k=0..[n/2]} 2^k*C(n+1,2*k+1)*a(k) for n>=0, with a(0)=1. O.g.f. A(x) satisfies: A(x/(1+x))/(1+x)^2 = A(2*x^2).
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EXAMPLE
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a(7) = Sum_{k=0..[7/2]} A105070(7,k)*a(k) =
8*(1) + 112*(2) + 224*(7) + 64*(20) = 3080.
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PROGRAM
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(PARI) a(n)=if(n==0, 1, sum(k=0, n\2, 2^k*binomial(n+1, 2*k+1)*a(k)))
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CROSSREFS
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Cf. A105070 (triangle), A118398 (A(x)^(1/2)).
Sequence in context: A115117 A029890 A095268 this_sequence A009697 A139012 A132605
Adjacent sequences: A118394 A118395 A118396 this_sequence A118398 A118399 A118400
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KEYWORD
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eigen,nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), May 08 2006
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