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A025180 a(n) = number of (s(0), s(1), ..., s(n)) such that s(i) is an integer, s(0) = 0, |s(1)| = 1, |s(i) - s(i-1)| <= 1 for i >= 2, s(n) = 2. Also a(n) = T(n,n-2), where T is the array defined in A025177. 3

%I

%S 1,2,7,20,60,176,518,1520,4461,13090,38423,112828,331487,974442,

%T 2866125,8434992,24838275,73181142,215729781,636275820,1877569134,

%U 5543095404,16372140876,48377825216,143009973875,422918975726,1251154692297

%N a(n) = number of (s(0), s(1), ..., s(n)) such that s(i) is an integer, s(0) = 0, |s(1)| = 1, |s(i) - s(i-1)| <= 1 for i >= 2, s(n) = 2. Also a(n) = T(n,n-2), where T is the array defined in A025177.

%F Conjecture: -(n+2)*(n-3)*a(n) +2*(2*n+1)*(n-3)*a(n-1) +(-n^2+10*n-18)*a(n-2) -3*(2*n-3)*(n-3)*a(n-3)=0. - _R. J. Mathar_, Feb 25 2015

%Y First differences of A014531. First differences are in A026069.

%K nonn

%O 2,2

%A _Clark Kimberling_

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Last modified May 8 13:26 EDT 2021. Contains 343666 sequences. (Running on oeis4.)