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 A224499 #12 Oct 13 2020 05:45:31 %S A224499 1,5,29,53,89,113,173,209,329,413,509,545,713,725,809,833,893,965, %T A224499 1013,1133,1169,1625,1649,1685,1733,1769,1925,2009,2045,2129,2273, %U A224499 2393,2465,2549,2825,2933,3065,3149,3329,3389,3413,3473,3605,3653,3665,3773 %N A224499 Numbers k such that if 2*k+1 divides 2^k+1 then 2*(k+1)+1 divides 2^(k+1)+1. %C A224499 First of a pair of consecutive Curzon numbers, where Curzon numbers are given by A224486. %H A224499 Amiram Eldar, <a href="/A224499/b224499.txt">Table of n, a(n) for n = 1..10000</a> %t A224499 CuQ[n_] := IntegerQ[(2^n + 1)/(2*n + 1)]; Select[Range[4000], CuQ[#] && CuQ[# + 1] &] %Y A224499 Cf. A000051, A224486. %K A224499 nonn %O A224499 1,2 %A A224499 _Jayanta Basu_, Apr 08 2013