A026086 Number of (s(0), s(1), ..., s(n)) such that 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) = 3; also a(n) = T(n,n-3), where T is the array defined in A026082.

1, 6, 16, 52, 156, 475, 1429, 4293, 12853, 38413, 114621, 341639, 1017407, 3027909, 9007017, 26783331, 79622595, 236662764, 703350798, 2090179494, 6211285598, 18457764317, 54851312871, 163009822939, 484469104651, 1439956255806

Offset

4,2

Links

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

Formula

Conjecture: (n+3)*a(n) +5*(-n-1)*a(n-1) +3*(n-5)*a(n-2) +(11*n-9)*a(n-3) +4*(-n+11)*a(n-4) +6*(-n+7)*a(n-5)=0. - R. J. Mathar, Jun 23 2013

Crossrefs

First differences of A026070.

Sequence in context: A367993 A301978 A275585 * A175659 A221270 A316984

Adjacent sequences: A026083 A026084 A026085 * A026087 A026088 A026089

Keyword

nonn

Author

Clark Kimberling

Status

approved