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Search: id:A090317
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| 1, 2, 7, 28, 118, 510, 2235, 9876, 43870, 195556, 873814, 3911168, 17527904, 78622982, 352911939, 1584927828, 7120769526, 32002212252, 143859840114, 646819996008, 2908670252676
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Apply the inverse of the Riordan array (1/(1-x^2),x/(1+x)^2) to 2^n. [From Paul Barry (pbarry(AT)wit.ie), Mar 13 2009]
Hankel transform is A079935. [From Paul Barry (pbarry(AT)wit.ie), Mar 13 2009]
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FORMULA
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a(n+1) = A000108(n+1) + Sum_ {k=0..n} a(n-k)*A001700(k); a(0) = 1.
G.f.: (1-x^2*c(x)^4)/(1-2x*c(x)^2), where c(x) is the g.f. of the Catalan numbers A000108. [From Paul Barry (pbarry(AT)wit.ie), Mar 13 2009]
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CROSSREFS
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Cf. A000108 A001700 A090285.
Sequence in context: A150647 A150648 A150649 this_sequence A150650 A150651 A151298
Adjacent sequences: A090314 A090315 A090316 this_sequence A090318 A090319 A090320
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KEYWORD
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easy,nonn
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AUTHOR
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DELEHAM Philippe (kolotoko(AT)wanadoo.fr), Jan 25 2004
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EXTENSIONS
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Term 15 corrected by Paul Barry (pbarry(AT)wit.ie), Mar 13 2009
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