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 A194578 #14 Apr 14 2017 12:18:08 %S A194578 1,3,43,68,93,228,612,1903,32292,44868,252072,36564198,55862807, %T A194578 134735264 %N A194578 Numbers n such that the sum of the first k divisors of n^2+1 is equal to n for some k. %C A194578 No further at least up to 10^7. %C A194578 No other terms up to 10^8. - _Michel Marcus_, Jan 17 2014 %C A194578 a(15) > 2.5*10^8. - _Giovanni Resta_, Apr 14 2017 %e A194578 The divisors of 43^2 + 1 are {1, 2, 5, 10, 25, 37, 50, 74, 185, 370, 925, 1850} and 1+2+5+10 + 25 = 43, hence 43 is in the list. %t A194578 Select[Range[10000000], MemberQ[Accumulate[Divisors[#^2+1]], #]&] %Y A194578 Cf. A185584. %K A194578 nonn %O A194578 1,2 %A A194578 _Michel Lagneau_, Aug 29 2011 %E A194578 a(12)-a(13) from _Michel Marcus_, Jan 17 2014 %E A194578 a(14) from _Giovanni Resta_, Apr 14 2017