This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A246648 #16 Jun 04 2024 05:52:35
%S A246648 0,1,7,127,227,647,1351,1907,3239,4607,5219,5975,11447,13159,13919,
%T A246648 21527,22049,23759,23939,24839,30959,31283,31583,31967,32767,37223,
%U A246648 46091,46511,47267,60479,65663,66527,78539,78599,81727,82799,84311,98405,102671,103967
%N A246648 Numbers k such that 2*k + 1 divides 2^(k+1) - 1.
%C A246648 These are the numbers k such that mean of the k-th row of the triangle at A027926 is an integer.
%C A246648 Numbers k such that 2*k + 1 divides 2^k + k. - _Thomas Ordowski_, Jun 04 2024
%H A246648 Robert Israel, <a href="/A246648/b246648.txt">Table of n, a(n) for n = 1..2000</a>
%e A246648 The sum of the numbers row 7 of the triangular array at A027926 is 2^8 - 1 = 255, and the number of numbers in row 7 is 15, and 255/15 = 17; thus 7 is in this sequence, and 17 is in A246649.
%p A246648 filter:= k -> 2 &^ (k+1) - 1 mod (2*k+1) = 0:
%p A246648 select(filter, [$0..2*10^5]); # _Robert Israel_, Jan 10 2020
%t A246648 z = 140000; u = Select[Range[0, z], IntegerQ[(2^(# + 1) - 1)/(2 # + 1)] &] (* A246648 *)
%t A246648 v = Table[(2^(u[[k]] + 1) - 1)/(2 u[[k]] + 1), {k, 1, 6}] (* A246649 *)
%Y A246648 Cf. A246637, A246649.
%K A246648 nonn,easy
%O A246648 1,3
%A A246648 _Clark Kimberling_, Sep 01 2014
%E A246648 Edited and offset changed by _Robert Israel_, Jan 10 2020