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A094667 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. 2
1, 4, 14, 48, 165, 572, 2001, 7056, 25042, 89320, 319793, 1148184, 4131009, 14885468, 53697270, 193862592, 700312381, 2530902676, 9149426897, 33083393640, 119645675898, 432748165304, 1565346866889, 5662560013488 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..24.

FORMULA

a(n) = (1/5)*sum(r=1..9, sin(r*Pi/10)*sin(2*r*Pi/5)*(2*cos(r*Pi/10))^(2*n+1)).

a(n) = 8*a(n-1) - 21*a(n-2) + 20*a(n-3) - 5*a(n-4).

G.f.: x*(-1+x)*(-1+3*x)/(1-8*x+21*x^2-20*x^3+5*x^4).

CROSSREFS

Sequence in context: A204089 A092489 A094827 * A099376 A002057 A047048

Adjacent sequences:  A094664 A094665 A094666 * A094668 A094669 A094670

KEYWORD

nonn

AUTHOR

Herbert Kociemba, Jun 14 2004

STATUS

approved

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Last modified October 18 03:17 EDT 2018. Contains 316302 sequences. (Running on oeis4.)