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 A193066 #11 Sep 24 2016 17:56:13 %S A193066 3,5,17,27,39,41,49,59,71,89,101,125,131,167,169,173,289,293,383,507, %T A193066 529,677,701,729,743,761,773,827,839,841,857,911,1091,1097,1163,1181, %U A193066 1193,1217,1373,1427,1487 %N A193066 Odd numbers N such that numerator(sigma(N^2)/N^2) is a prime. %C A193066 Square roots of the terms of A193065. See there for more comments. %H A193066 Harvey P. Dale, <a href="/A193066/b193066.txt">Table of n, a(n) for n = 1..1000</a> %F A193066 a(n) = A000196(A193065(n)). %t A193066 Select[Range[1,1501,2],PrimeQ[Numerator[DivisorSigma[1,#^2]/#^2]]&] (* _Harvey P. Dale_, Sep 24 2016 *) %o A193066 (PARI) forstep(N=1, 1e7, 2, isprime(numerator(sigma(N^2)/N^2)) && print1(N", ")) %K A193066 nonn %O A193066 1,1 %A A193066 _M. F. Hasler_, Jul 15 2011