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 A140769 #7 Oct 01 2019 07:28:31 %S A140769 2,3,4,5,8,9,10,11,14,15,16,17,23,26,27,28,29,32,33,34,35,38,39,44,45, %T A140769 46,47,50,51,52,53,56,57,58,59,62,65,68,69,70,71,74,75,76,77,82,83,86, %U A140769 87,88,89,92,93,94,95,98,99,104,107,112,113,116,117,118,119,122,123,124 %N A140769 Numbers n such that consecutive Mersenne numbers A000225(n-1) = M(n-1) = 2^(n-1) - 1 and A000225(n) = M(n) = 2^n - 1 are both squarefree. %D A140769 J.-M. De Koninck, Ces nombres qui nous fascinent, Footnote pp 18, Ellipses, Paris 2008. %H A140769 Amiram Eldar, <a href="/A140769/b140769.txt">Table of n, a(n) for n = 1..629</a> %Y A140769 Cf. A000225, A005117. %K A140769 nonn %O A140769 1,1 %A A140769 _Lekraj Beedassy_, Jul 13 2008