A026085 - OEIS

A026085

a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0, |s(i) - s(i-1)| = 1 for i = 1,2,3; |s(i) - s(i-1)| <= 1 for i >= 4, s(n) = 2. Also a(n) = T(n,n-2), where T is the array defined in A026082.

4, 8, 27, 76, 226, 660, 1939, 5688, 16704, 49072, 144254, 424296, 1248728, 3677184, 10834416, 31939584, 94205772, 277997400, 820747275, 2424232956, 7163519202, 21176638868, 62626464319, 185276853192, 548326714720, 1623325361424

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OFFSET

4,1

LINKS

Table of n, a(n) for n=4..29.

FORMULA

Conjecture: (n+2)*a(n) +(-5*n-1)*a(n-1) +4*(n-4)*a(n-2) +8*(n-1)*a(n-3) +(-5*n+34)*a(n-4) +3*(-n+7)*a(n-5)=0. - R. J. Mathar, Jun 23 2013

CROSSREFS

First differences of A026069.

Sequence in context: A100411 A065405 A279627 * A036720 A110132 A099513

Adjacent sequences: A026082 A026083 A026084 * A026086 A026087 A026088

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved