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 A248549 #8 Aug 16 2019 15:12:11 %S A248549 194,316,416,804,904,926,1026,1170,1270,1414,1536,1780,2024,2490,2734, %T A248549 2856,3000,3100,3244,3344,3366,3610,3954,3976,4320,4564,4830,4930, %U A248549 5074,5196,5540,5684,6394,6416,6516,6760,6904,7004,7126,7270,7370,7514,7614,7736 %N A248549 Numbers n such that the smallest prime divisor of n^2+1 is 61. %C A248549 Or numbers n such that the smallest prime divisor of n^2+1 is A002313(9). %C A248549 a(n)== 50 or 72 (mod 122). %H A248549 Amiram Eldar, <a href="/A248549/b248549.txt">Table of n, a(n) for n = 1..10000</a> %e A248549 194 is in the sequence because 194^2+1= 61*617. %t A248549 lst={};Do[If[FactorInteger[n^2+1][[1, 1]]==61, AppendTo[lst, n]], {n, 2, 10000}]; lst %t A248549 p = 61; ps = Select[Range[p - 1], Mod[#, 4] != 3 && PrimeQ[#] &]; Select[Range[8000], Divisible[(nn = #^2 + 1), p] && ! Or @@ Divisible[nn, ps] &] (* _Amiram Eldar_, Aug 16 2019 *) %Y A248549 Cf. A089120, A002313, A209874, A248527-A248531, A248549-A248553. %K A248549 nonn,easy %O A248549 1,1 %A A248549 _Michel Lagneau_, Oct 08 2014