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Search: id:A094667
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| A094667 |
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Number of (s(0), s(1), ..., s(2n+1)) such that 0 < s(i) < 10 and |s(i) - s(i-1)| = 1 for i = 1,2,....,2n+1, s(0) = 1, s(2n+1) = 4. |
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+0
1
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| 1, 4, 14, 48, 165, 572, 2001, 7056, 25042, 89320, 319793, 1148184, 4131009, 14885468, 53697270, 193862592, 700312381, 2530902676, 9149426897, 33083393640, 119645675898, 432748165304, 1565346866889, 5662560013488
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OFFSET
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1,2
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FORMULA
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a(n)=(1/5)*Sum(r, 1, 9, Sin(r*Pi/10)Sin(2*r*Pi/5)(2Cos(r*Pi/10))^(2n+1)) a(n)=8a(n-1)-21a(n-2)+20a(n-3)-5a(n-4) G.f.: x(-1+x)(-1+3x)/(1-8x+21x^2-20x^3+5x^4)
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CROSSREFS
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Sequence in context: A007070 A092489 A094827 this_sequence A002057 A099376 A047048
Adjacent sequences: A094664 A094665 A094666 this_sequence A094668 A094669 A094670
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KEYWORD
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nonn
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AUTHOR
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Herbert Kociemba (kociemba(AT)t-online.de), Jun 14 2004
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