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 A231876 #13 Apr 25 2017 10:02:05 %S A231876 2,3,4,5,7,8,9,11,12,13,16,17,19,20,23,24,25,27,28,29,31,32,36,37,40, %T A231876 41,43,44,47,48,49,52,53,56,59,61,64,67,68,71,72,73,76,79,80,81,83,88, %U A231876 89,90,92,96,97,100,101,103,104,107,108,109,112,113,116,121,124,125,126,127,128,131,136,137,139,144,148,149 %N A231876 Numbers n such that omega(n)^2 (cf. A001221) divides n. %C A231876 Includes all prime powers (A246655), as well as 4*A246655. - _Robert Israel_, Apr 25 2017 %H A231876 G. C. Greubel, <a href="/A231876/b231876.txt">Table of n, a(n) for n = 1..1100</a> %p A231876 select(n -> n mod nops(numtheory:-factorset(n))^2 = 0, [$2..1000]); # _Robert Israel_, Apr 25 2017 %t A231876 Select[Range[2, 500], Mod[#, PrimeNu[#]^2] == 0 &] (* _G. C. Greubel_, Apr 24 2017 *) %o A231876 (PARI) isok(n) = !(n % omega(n)^2); \\ _Michel Marcus_, Apr 25 2017 %Y A231876 Cf. A001221, A075592, A185307, A001222, A074946, A134334, A231877 (complement). %Y A231876 Cf. A246655. %K A231876 nonn %O A231876 1,1 %A A231876 _N. J. A. Sloane_, Nov 17 2013