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 A262978 #54 Sep 08 2022 08:46:14
%S A262978 1,2,4,5,7,8,11,13,14,16,17,19,22,23,25,26,28,29,31,32,34,35,37,38,41,
%T A262978 43,44,46,47,49,52,53,56,58,59,61,62,64,65,67,71,73,74,76,77,79,82,83,
%U A262978 85,86,88,89,91,92,94,95,97,98,101,103,104,106,107,109,112,113,115,116,118,119
%N A262978 Exponents n such that 2^n-1 and 2^n+1 are squarefree.
%H A262978 Amiram Eldar, <a href="/A262978/b262978.txt">Table of n, a(n) for n = 1..608</a>
%F A262978 2^a(n) = A269758(n).
%e A262978 a(4) = 5 because 2^5 - 1 = 31 and 2^5 + 1 = 33 are squarefree numbers.
%t A262978 Select[Range[120],AllTrue[2^#+{1,-1},SquareFreeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Dec 20 2019 *)
%o A262978 (Magma) [n: n in [1..120] | IsSquarefree(2^n-1) and IsSquarefree(2^n+1)];
%o A262978 (PARI) is(n)=issquarefree(2^n-1) && issquarefree(2^n+1) \\ _Charles R Greathouse IV_, May 02 2016
%Y A262978 Cf. A000961, A229303, A269758.
%K A262978 nonn,easy
%O A262978 1,2
%A A262978 _Juri-Stepan Gerasimov_, May 01 2016