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A094825 Number of (s(0), s(1), ..., s(2n)) such that 0 < s(i) < 10 and |s(i) - s(i-1)| = 1 for i = 1,2,....,2n, s(0) = 1, s(2n) = 7. 2
1, 7, 35, 153, 624, 2444, 9333, 35055, 130207, 479941, 1759616, 6427032, 23412105, 85121783, 309062619, 1121050449, 4063463728, 14721293860, 53313308477, 193023319071, 698715633111, 2528895064637, 9152032060800, 33118656195888 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

LINKS

Table of n, a(n) for n=3..26.

Index entries for linear recurrences with constant coefficients, signature (8,-21,20,-5)

FORMULA

a(n)=(1/5)*Sum(r, 1, 9, Sin(r*Pi/10)Sin(7*r*Pi/10)(2Cos(r*Pi/10))^(2n)).

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

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

a(n) = -A001906(n)/2 + A020876(n)/10. - R. J. Mathar, Jun 24 2011

MATHEMATICA

LinearRecurrence[{8, -21, 20, -5}, {1, 7, 35, 153}, 30] (* Harvey P. Dale, Jan 16 2015 *)

CROSSREFS

Cf. A094865 (partial sums).

Sequence in context: A223621 A215510 A240423 * A022635 A217274 A000588

Adjacent sequences:  A094822 A094823 A094824 * A094826 A094827 A094828

KEYWORD

nonn

AUTHOR

Herbert Kociemba, Jun 15 2004

STATUS

approved

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Last modified February 18 23:26 EST 2018. Contains 299330 sequences. (Running on oeis4.)