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Search: id:A099503
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| A099503 |
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Expansion of 1/(1-4x+x^3). |
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+0
3
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| 1, 4, 16, 63, 248, 976, 3841, 15116, 59488, 234111, 921328, 3625824, 14269185, 56155412, 220995824, 869714111, 3422701032, 13469808304, 53009519105, 208615375388, 820991693248, 3230957253887, 12715213640160, 50039862867392
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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A transform of A000302 under the mapping g(x)->(1/(1+x^3))g(x/(1+x^3)).
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FORMULA
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a(n)=4a(n-1)-a(n-3); a(n)=sum{k=0..floor(n/3), binomial(n-2k, k)(-1)^k*4^(n-3k)}.
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MAPLE
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K:=1/(1+4*z-z^3): Kser:=series(K, z=0, 30): seq(abs(coeff(Kser, z, n)), n= 0..23); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Nov 08 2007
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CROSSREFS
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Cf. A076264, A000071, A099504.
Adjacent sequences: A099500 A099501 A099502 this_sequence A099504 A099505 A099506
Sequence in context: A034542 A071264 A077822 this_sequence A119376 A022030 A135450
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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), Oct 20 2004
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