login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

Integers of the form (2^j - 1)*(2^k + 1), j >= 0, k >= 0.
1

%I #23 Feb 23 2018 09:12:51

%S 0,2,3,5,6,9,14,15,17,21,27,30,33,35,45,51,62,63,65,75,93,99,119,126,

%T 129,135,155,189,195,231,254,255,257,279,315,381,387,455,495,510,513,

%U 527,567,635,765,771,903,975,1022,1023,1025,1071,1143,1275,1533,1539

%N Integers of the form (2^j - 1)*(2^k + 1), j >= 0, k >= 0.

%H Ivan Neretin, <a href="/A175095/b175095.txt">Table of n, a(n) for n = 1..10000</a>

%t mx = 1600; Join[{0}, Most@ Union@ Flatten@ Table[(2^j -1) (2^k +1), {j, Log2@ mx}, {k, 0, Log2[mx/(2^j -1)]} ]] (* _Ivan Neretin_, Feb 12 2018 and slightly modified by _Robert G. Wilson v_, Feb 13 2018 *)

%Y Cf. A000051, A000225.

%K easy,nonn

%O 1,2

%A _Leroy Quet_, Feb 01 2010

%E Extended by _Ray Chandler_ and _R. J. Mathar_, Feb 06 2010