A026070 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; |s(i) - s(i-1)| <= 1 for i >= 3, s(n) = 3. Also a(n) = T(n,n-3), where T is the array defined in A024996.

1, 2, 8, 24, 76, 232, 707, 2136, 6429, 19282, 57695, 172316, 513955, 1531362, 4559271, 13566288, 40349619, 119972214, 356634978, 1059985776, 3150165270, 9361450868, 27819215185, 82670528056, 245680350995, 730149455646, 2170105711452

Offset: 3

Author

Clark Kimberling

Keywords

• nonn

Crossrefs

First differences of A025181. Second differences of A014532.

Formula

Conjecture: (n+3)*a(n) +(-5*n-6)*a(n-1) +(3*n-11)*a(n-2) +(11*n-8)*a(n-3) +2*(-2*n+17)*a(n-4) +6*(-n+6)*a(n-5)=0. - R. J. Mathar, Jun 23 2013