A166986 a(n) = 2*floor((n+2)/log(2)) - 4.

4, 6, 10, 12, 16, 18, 20, 24, 26, 30, 32, 36, 38, 42, 44, 46, 50, 52, 56, 58, 62, 64, 68, 70, 72, 76, 78, 82, 84, 88, 90, 94, 96, 98, 102, 104, 108, 110, 114, 116, 120, 122, 124, 128, 130, 134, 136, 140, 142, 146, 148, 150, 154, 156, 160, 162, 166, 168, 172, 174, 176

Offset: 1

Author

Stephen Crowley, Oct 26 2009

Keywords

• easy
• nonn

Comments

With a different offset, partial sums of A022934, cf. formula.

The first terms appear to satisfy a linear recurrence relation of order 10 (or higher if more terms are included), but this can be proved to be impossible, cf. R. Israel's post to the SeqFan list. - M. F. Hasler, Apr 11 2019

Links

• G. C. Greubel, Table of n, a(n) for n = 1..1000
• R. Israel, Re: Differences between linear recurrence, program(s) and b-file, SeqFan list, Apr 11 2019

Crossrefs

Cf. A022934.

Programs

Magma

[2*Floor((n+2)/Log(2)) - 4: n in [1..80]]; // Vincenzo Librandi, Jul 06 2015

Maple

seq(2*floor((n+2)/log(2))-4, n=1..100); # Robert Israel, Apr 11 2019

Mathematica

Table[2 Floor[(n + 2)/Log[2]] - 4, {n, 1, 70}] (* Vincenzo Librandi, Jul 06 2015 *)

PARI

vector( 80, n, 2*floor((n+2)/log(2)) - 4) \\ Michel Marcus, Jul 06 2015

PARI

A166986(n)=(n+2)\log(2)*2-4 \\ M. F. Hasler, Apr 11 2019, corrected by Charles R Greathouse IV, Oct 19 2022

Formula

a(n) = 2*floor((n+2)/log(2)) - 4.

a(n) = 2*Sum_{k=2,..,n+1} A022934(k).