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Search: id:A115967
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| A115967 |
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Expansion of 1/(2*sqrt(1-2*x-3*x^2)-1). |
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+0
3
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| 1, 2, 8, 28, 104, 384, 1428, 5316, 19820, 73948, 276044, 1030796, 3850048, 14382248, 53732172, 200759004, 750134520, 2802980640, 10474015164, 39139487292, 146259311592, 546558514368, 2042458815324, 7632600834924, 28522903136796
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Row sums of number triangle A116392.
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FORMULA
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a(n)=sum{k=0..n, A116392(n,k)}.
G.f.: A(x)^2/(2*A(x)-A(x)^2) where A(x) is the g.f. of the central trinomial coefficients A002426.
Also, expansion of (1+2*sqrt(1-2*x-3*x^2))/(3-8*x-12*x^2).
Hankel transform is A000302, A000302(n)=4^n . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jun 22 2007
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CROSSREFS
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Sequence in context: A056711 A114590 A133592 this_sequence A150714 A122447 A150715
Adjacent sequences: A115964 A115965 A115966 this_sequence A115968 A115969 A115970
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Feb 03 2006
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EXTENSIONS
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Entry revised by N. J. A. Sloane (njas(AT)research.att.com), Apr 10 2006
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