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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.
0
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
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
KEYWORD
nonn
STATUS
approved