A029749 Numbers of the form 2^k times 1, 5 or 7.

1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 32, 40, 56, 64, 80, 112, 128, 160, 224, 256, 320, 448, 512, 640, 896, 1024, 1280, 1792, 2048, 2560, 3584, 4096, 5120, 7168, 8192, 10240, 14336, 16384, 20480, 28672, 32768, 40960, 57344, 65536, 81920, 114688, 131072

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (0,0,2).

Crossrefs

Cf. A000079, A005009, A029746, A029748, A094958.

Programs

Mathematica

CoefficientList[Series[-(3 x^4 + 3 x^3 + 4 x^2 + 2 x + 1) / (2 x^3 - 1), {x, 0, 40}], x] (* Vincenzo Librandi, Jul 20 2013 *)

Formula

From Colin Barker, Jul 19 2013: (Start)

a(n) = 2*a(n-3) for n>4.

G.f.: -(3*x^4 + 3*x^3 + 4*x^2 + 2*x + 1) / (2*x^3 - 1). (End)

Sum_{n>=0} 1/a(n) = 94/35. - Amiram Eldar, Jan 21 2022

Extensions

More terms from Colin Barker, Jul 19 2013