A162396 a(n) = 2*a(n-2) for n > 2; a(1) = 5, a(2) = 2.

5, 2, 10, 4, 20, 8, 40, 16, 80, 32, 160, 64, 320, 128, 640, 256, 1280, 512, 2560, 1024, 5120, 2048, 10240, 4096, 20480, 8192, 40960, 16384, 81920, 32768, 163840, 65536, 327680, 131072, 655360, 262144, 1310720, 524288, 2621440, 1048576, 5242880

Offset

1,1

Comments

Binomial transform is A162268. Fifth binomial transform is A083880 without initial 1.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (0,2).

Formula

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

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

Maple

A162396:=n->(3/2-(-1)^n)*2^(1/4*(2*n+3+(-1)^n)): seq(A162396(n), n=1..60); # Wesley Ivan Hurt, Oct 08 2017

Mathematica

CoefficientList[Series[(5 + 2*x)/(1 - 2*x^2), {x, 0, 40}], x] (* Wesley Ivan Hurt, Oct 08 2017 *)
RecurrenceTable[{a[1]==5, a[2]==2, a[n]==2 a[n-2]}, a, {n, 40}] (* Vincenzo Librandi, Oct 09 2017 *)

Prog

(Magma) [ n le 2 select 8-3*n else 2*Self(n-2): n in [1..41] ];
(Magma) [Floor((3/2-(-1)^n)*2^(1/4*(2*n+3+(-1)^n))):  n in [1..50]]; // Vincenzo Librandi, Oct 09 2017

Crossrefs

Cf. A083880, A162255, A162268.

Sequence in context: A196385 A178714 A036121 * A194046 A249368 A055682

Adjacent sequences: A162393 A162394 A162395 * A162397 A162398 A162399

Keyword

nonn,easy

Author

Klaus Brockhaus, Jul 02 2009

Extensions

G.f. corrected, formula simplified, comment added by Klaus Brockhaus, Sep 18 2009

Status

approved