A062107 - OEIS

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

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..27.

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

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)

MAPLE

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

CROSSREFS

Except for initial terms, same as A005052.

Sequence in context: A026109 A026327 A014531 * A269800 A033113 A360714

Adjacent sequences: A062104 A062105 A062106 * A062108 A062109 A062110

KEYWORD

nonn

AUTHOR

Antti Karttunen, May 30 2001

STATUS

approved