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Search: id:A055988
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A055988 Sequence is its own 4th difference. +0
5
1, 2, 7, 26, 95, 345, 1252, 4544, 16493, 59864, 217286, 788674, 2862617, 10390321, 37713313, 136886433, 496850954, 1803399103, 6545722210, 23758733815, 86236081273, 313007493212, 1136110191472, 4123691589365, 14967590689568 (list; graph; listen)
OFFSET

1,2

COMMENT

Row sums of Riordan array (1/(1-x), x/(1-x)^4), A109960. - Paul Barry (pbarry(AT)wit.ie), Jul 06 2005

FORMULA

a(n)=5a(n-1)-6a(n-2)+4a(n-3)-a(n-4) =a(n-1)+A055991(n-1) =A055989(n)-A055989(n-1) =A055990(n)-2*A055990(n-1)+A055990(n-2)

G.f.: (1-x)^3/(1-5x+6x^2-4x^3+x^4); a(n)=sum{k=0..n, binomial(n+3k, 4k)}. - Paul Barry (pbarry(AT)wit.ie), Jul 06 2005

CROSSREFS

Cf. A055989, A055990, A055991 for the other differences of a(n). See A000079, A001906, A052529 for examples of sequences which are respectively their own first, second, and third differences.

Sequence in context: A134063 A087448 A129273 this_sequence A087096 A001075 A113436

Adjacent sequences: A055985 A055986 A055987 this_sequence A055989 A055990 A055991

KEYWORD

nonn

AUTHOR

Henry Bottomley (se16(AT)btinternet.com), Jun 02 2000

EXTENSIONS

More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jun 05 2000

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Last modified July 26 13:41 EDT 2008. Contains 142293 sequences.


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