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URL: https://oeis.org/A026084

⇱ A026084 - OEIS

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A026084
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) = 1. Also a(n) = T(n,n-1), where T is the array defined in A026082.
0
3, 13, 33, 98, 278, 804, 2320, 6723, 19515, 56769, 165421, 482793, 1411049, 4129323, 12098151, 35482857, 104169033, 306087111, 900134883, 2649106752, 7801834068, 22992061134, 67799076002, 200040038589, 590529542053, 1744148984223
OFFSET
4,1
FORMULA
Conjecture: (n+1)*a(n) +3*(-n+1)*a(n-1) +(-n-9)*a(n-2) +3*(n-5)*a(n-3)=0. - R. J. Mathar, Jun 23 2013
CROSSREFS
First differences of A024998.
Sequence in context: A252979 A332366 A033943 * A211801 A016061 A154154
KEYWORD
nonn
STATUS
approved