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A026083 a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0 = s(n), |s(i) - s(i-1)| = 1 for i = 1,2,3; |s(i) - s(i-1)| <= 1 for i >= 4. Also a(n) = T(n,n), where T is the array defined in A026082. 0
6, 12, 38, 104, 300, 856, 2464, 7104, 20550, 59580, 173118, 503960, 1469546, 4291644, 12550290, 36746592, 107712306, 316050372, 928224594, 2728494360, 8026707864, 23630376000, 69614498268, 205212650272, 605292727450, 1786351811556 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

COMMENTS

Third differences of the central trinomial numbers (A002426). - T. D. Noe, Mar 16 2005

LINKS

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

FORMULA

Conjecture: n*a(n) +(-3*n+5)*a(n-1) +(-n-6)*a(n-2) +3*(n-5)*a(n-3)=0. - R. J. Mathar, Jun 22 2013

CROSSREFS

Equals 2 * A024998(n-1). First differences of A024997.

Sequence in context: A038266 A117596 A096377 * A215179 A128453 A185616

Adjacent sequences:  A026080 A026081 A026082 * A026084 A026085 A026086

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified April 20 06:17 EDT 2014. Contains 240779 sequences.