A162813 a(n) = 3*a(n-2) for n > 2; a(1) = 5, a(2) = 3.

5, 3, 15, 9, 45, 27, 135, 81, 405, 243, 1215, 729, 3645, 2187, 10935, 6561, 32805, 19683, 98415, 59049, 295245, 177147, 885735, 531441, 2657205, 1594323, 7971615, 4782969, 23914845, 14348907, 71744535, 43046721, 215233605, 129140163, 645700815, 387420489

Offset: 1

Author

Klaus Brockhaus, Jul 20 2009

Keywords

• nonn
• easy

Comments

Binomial transform is A162562.

Links

• Index entries for linear recurrences with constant coefficients, signature (0,3).

Crossrefs

Cf. A162562, A162436, A162766.

Programs

Magma

[ n le 2 select 7-2*n else 3*Self(n-2): n in [1..34] ];

Mathematica

nxt[{a_,b_}]:={b,3a}; NestList[nxt,{5,3},40][[All,1]] (* or *) LinearRecurrence[ {0,3},{5,3},40] (* Harvey P. Dale, May 29 2021 *)

Formula

a(n) = (3-2*(-1)^n)*3^(1/4*(2*n-1+(-1)^n)).

G.f.: x*(5+3*x)/(1-3*x^2)

Extensions

a(35)-a(36) from Yifan Xie, Jul 20 2022