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 A125236 #12 Sep 23 2019 13:27:27 %S A125236 3,5,6,7,9,10,11,14,15,17,18,22,24,26,28,29,30,31,33,34,35,44,47,50, %T A125236 56,58,61,65,66,67,68,69,71,72,74,75,80,85,91,94,96,97,100,101,102, %U A125236 104,116,118,120,121,124,125,127,131,134,136,139,144,148,149,152,164,166,170 %N A125236 Numbers n for which the absolute value of the abundance of n^2 is a prime number. %H A125236 Amiram Eldar, <a href="/A125236/b125236.txt">Table of n, a(n) for n = 1..10000</a> %e A125236 n=5: n^2=25, sigma(25)=25+5+1=31, 2*25=50, abundance=-19. %t A125236 Select[Range[170], PrimeQ[DivisorSigma[1, #^2] - 2*#^2] &] (* _Amiram Eldar_, Sep 23 2019 *) %o A125236 (PARI) for(n=1,170,if(isprime(abs(sigma(n^2)-2*n^2)),print1(n,","))) \\ _Klaus Brockhaus_, Nov 25 2006 %Y A125236 Cf. A088005. %K A125236 nonn %O A125236 1,1 %A A125236 _Jason G. Wurtzel_, Nov 25 2006 %E A125236 More terms from _Klaus Brockhaus_, Nov 25 2006