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 A264050 #32 Nov 28 2015 19:33:37
%S A264050 3,3,3,3,5,3,3,7,9,7,5,3,17,27,3,3,29,3,21,7,17,15,9,43,35,15,29,3,11,
%T A264050 3,11,15,17,25,53,31,9,7,23,15,27,15,29,7,59,15,5,21,69,55,21,21,5,
%U A264050 159,3,81,9,69,131,33,15,135,29,13,131,9,3,33,29,25,11,15,29,37,33
%N A264050 a(n) = least m > 1 such that m + 2^n is prime.
%C A264050 The definition is similar to Fortunate numbers (A005235) but uses 2^n instead of primorial A002110(n).
%C A264050 Terms a(n) are often but not always prime; sometimes they are prime powers or semiprimes or have a more general form.
%C A264050 An analog of Fortune's conjecture for this sequence would be "a(n) is either a prime power or a semiprime." But even this relaxed conjecture is disproved by, e.g., a(62)=135, a(93)=a(97)=105, a(99)=255.
%C A264050 By definition, a(n) >= A013597(n). The integers n such that a(n) > A013597(n) are those with A013597(n)=1, i.e., 1, 2, 4, 8, 16, and then? - _Michel Marcus_, Nov 06 2015
%H A264050 Charles R Greathouse IV, <a href="/A264050/b264050.txt">Table of n, a(n) for n = 1..2000</a>
%e A264050 a(56)=81 because m=81 is the least m > 1 such that m + 2^56 is prime.
%t A264050 Table[m = 2; While[! PrimeQ[m + 2^n], m++]; m, {n, 75}] (* _Michael De Vlieger_, Nov 06 2015 *)
%o A264050 (PARI) a(n)=my(m=2);while(!isprime(m+2^n),m++);m \\ _Anders Hellström_, Nov 02 2015
%o A264050 (PARI) a(n)=nextprime(2^n+2)-2^n \\ _Charles R Greathouse IV_, Nov 02 2015
%Y A264050 Cf. A005235, A013597, A092131, A263925.
%K A264050 nonn
%O A264050 1,1
%A A264050 _Alexei Kourbatov_, Nov 02 2015
%E A264050 a(60) corrected by _Charles R Greathouse IV_, Nov 02 2015