A062107 Diagonal of table A062104.

0, 1, 3, 10, 30, 90, 270, 810, 2430, 7290, 21870, 65610, 196830, 590490, 1771470, 5314410, 15943230, 47829690, 143489070, 430467210, 1291401630, 3874204890, 11622614670, 34867844010, 104603532030, 313810596090, 941431788270

Offset: 1

Author

Antti Karttunen, May 30 2001

Keywords

• nonn

Links

• Index entries for linear recurrences with constant coefficients, signature (3).

Crossrefs

Except for initial terms, same as A005052.

Programs

Maple

[seq(ChessPawnTriangle(j,j),j=1..50)];

Formula

a(n) = 10*3^(n-4) for n >= 4.

From Paul Barry, Oct 15 2004: (Start)

G.f.: x^2(1+x^2)/(1-3x);

a(n) = Sum_{k=0..n-2} 3^(n-k-2)binomial(1, k/2)(1+(-1)^k)/2. (End)