cp's OEIS Frontend

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.

%I A025180 #6 Feb 25 2015 15:53:50
%S A025180 1,2,7,20,60,176,518,1520,4461,13090,38423,112828,331487,974442,
%T A025180 2866125,8434992,24838275,73181142,215729781,636275820,1877569134,
%U A025180 5543095404,16372140876,48377825216,143009973875,422918975726,1251154692297
%N 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.
%F A025180 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 A025180 First differences of A014531. First differences are in A026069.
%K A025180 nonn
%O A025180 2,2
%A A025180 _Clark Kimberling_