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, 2824295364810, 8472886094430, 25418658283290, 76255974849870

Offset

1,3

Links

Paolo Xausa, Table of n, a(n) for n = 1..1000

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)/(1-3*x);

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

a(n) = floor(10*3^(n-4)). - Paolo Xausa, Mar 10 2026

Maple

series(x^2*(1+x^2)/(1-3*x), x, 40):
seq(coeff(%, x, n), n=1..35);

Mathematica

Floor[10*3^Range[-3, 30]] (* Paolo Xausa, Mar 10 2026 *)

Prog

(PARI) a(n)=if(n>3, 10*3^(n-4), [0, 1, 3][n]) \\ Charles R Greathouse IV, May 16 2026

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,easy

Author

Antti Karttunen, May 30 2001

Extensions

More terms from Paolo Xausa, Mar 10 2026

Status

approved