A291778 a(n) = 2^floor(2*n/3).

1, 1, 2, 4, 4, 8, 16, 16, 32, 64, 64, 128, 256, 256, 512, 1024, 1024, 2048, 4096, 4096, 8192, 16384, 16384, 32768, 65536, 65536, 131072, 262144, 262144, 524288, 1048576, 1048576, 2097152, 4194304, 4194304, 8388608, 16777216, 16777216, 33554432, 67108864, 67108864

Offset: 0

Author

Don Reble and N. J. A. Sloane, Aug 31 2017

Keywords

• nonn

Links

• Robert Israel, Table of n, a(n) for n = 0..4978
• Index entries for linear recurrences with constant coefficients, signature (0,0,4).

Crossrefs

Cf. A004523, A291779.

Programs

Maple

seq(2^floor(2*n/3),n=0..100); # Robert Israel, Sep 01 2017

Mathematica

LinearRecurrence[{0, 0, 4}, {1, 1, 2}, 41] (* Jean-François Alcover, Apr 02 2019 *)

Formula

a(n) = 2^A004523(n).

G.f.: (1+x+2*x^2)/(1-4*x^3). - Robert Israel, Sep 01 2017

From Amiram Eldar, Sep 29 2022: (Start)

Sum_{n>=0} 1/a(n) = 10/3.

Sum_{n>=0} (-1)^n/a(n) = 2/5. (End)