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 A319245 #17 Sep 17 2018 03:15:47 %S A319245 0,1,17,37,77,197,513,993,1837,2617,2637,4097,5437,65537,261633, %T A319245 364137,437837,2097153,16777217,32761917,54644032237,68719476737, %U A319245 137438953473,1099511627777 %N A319245 Numbers k such that k^2 + 1 divides 2^k + 8. %C A319245 Prime terms are 17, 37, 197, 2617, 5437, 65537, 437837, ... %C A319245 Numbers t such that 2^t + 1 is a term are 4, 9, 12, 16, 21, 24, 36, 37, 40, 45, 49, 52, 57, 64, 69, 76, 84, 96, ... %t A319245 Select[Range[0, 9999], Divisible[2^# + 8, #^2 + 1] &] (* _Alonso del Arte_, Sep 16 2018 *) %o A319245 (PARI) isok(n)=Mod(2, n^2+1)^n==-8; %Y A319245 Cf. A247220, A319216, A319233. %K A319245 nonn,more %O A319245 1,3 %A A319245 _Altug Alkan_, Sep 15 2018 %E A319245 a(21)-a(24) from _Hiroaki Yamanouchi_, Sep 16 2018