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Search: id:A086622
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| 1, 2, 5, 12, 30, 76, 197, 520, 1398, 3820, 10594, 29768, 84620, 243000, 704045, 2055760, 6043750, 17875020, 53148310, 158773320, 476311940, 1434313960, 4333867170, 13135533552, 39924668220, 121661345656, 371612931492
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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G.f.: A(x) = 1/(1-2x) + x^2*A(x)^2.
a(n)=sum{k=0..floor(n/2), binomial(n-k, k)binomial(2k, k)2^(n-2k)/(k+1)} - Paul Barry (pbarry(AT)wit.ie), Nov 13 2004
Hankel transform of a(n) is 1,1,1,....; Hankel transform of a(n+1) is A009531(n+2). - Paul Barry (pbarry(AT)wit.ie), Nov 06 2007
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CROSSREFS
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Cf. A086620 (table), A086621 (diagonal).
Adjacent sequences: A086619 A086620 A086621 this_sequence A086623 A086624 A086625
Sequence in context: A002026 A105695 A026938 this_sequence A024851 A103287 A136704
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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), Jul 24 2003
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