A115188 Second diagonal (M=2) of triangle A115154 (called Y(3,1)).

1, 13, 115, 1036, 9688, 93571, 927523, 9387580, 96634294, 1008719002, 10653244294, 113630599852, 1222361061310, 13246563382735, 144479425979635, 1584810988780420, 17471975574010630, 193493968384827670

Offset

0,2

Links

Table of n, a(n) for n=0..17.

Formula

a(n)= A115154(n+1,n+1), n>=0.

Recurrence: a(n)= b(n) - 3*b(n-1), with b(n):= A064063(n+2), n>=0.

G.f.: ((-3+2*x) + 3*(1-3*x)*c(3*x))/(x*(2+x)), with the o.g.f. c(x) of A000108 (Catalan).

Example

115 = a(2) = A064063(4) - 3* A064063(3) = 190 - 3*25.

Crossrefs

Sequence in context: A287471 A016765 A362514 * A155621 A232319 A296332

Adjacent sequences: A115185 A115186 A115187 * A115189 A115190 A115191

Keyword

nonn,easy

Author

Wolfdieter Lang, Feb 23 2006

Status

approved