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Search: id:A034015
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| 1, 5, 33, 249, 2033, 17485, 156033, 1431281, 13412193, 127840085, 1235575201, 12080678505, 119276490193, 1187542872989, 11909326179841, 120191310803937, 1219780566014657, 12440630635406245, 127446349676475425
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OFFSET
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0,2
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COMMENT
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Series reversion of x(Sum_{k>=0} a(k)(-x^2)^k) is Sum_{k odd} C(k)x^k where C() is Catalan numbers A000108.
Series reversion of x(Sum_{k>=0} a(k)(-x)^k) is A000337(x). (Michael Somos)
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PROGRAM
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(PARI) a(n)=if(n<0, 0, sum(i=0, n, 2^i*binomial(2*n+2, i)*binomial(n+1, i+1))/(n+1))
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CROSSREFS
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Sequence in context: A084131 A084771 A153398 this_sequence A056159 A061253 A111530
Adjacent sequences: A034012 A034013 A034014 this_sequence A034016 A034017 A034018
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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