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 A302491 #14 Nov 07 2023 05:08:47 %S A302491 2,3,5,11,13,17,29,31,41,43,47,59,67,73,79,83,101,109,113,127,137,139, %T A302491 149,157,163,167,179,181,191,199,211,233,241,257,269,271,277,283,293, %U A302491 313,317,331,347,349,353,367,373,389,397,401,421,431,439,443,449,461 %N A302491 Prime numbers of squarefree index. %C A302491 A prime index of n is a number m such that prime(m) divides n. %H A302491 Robert Israel, <a href="/A302491/b302491.txt">Table of n, a(n) for n = 1..10000</a> %F A302491 a(n) = A000040(A005117(n)). %F A302491 a(n) ~ kn log n, where k = Pi^2/6. - _Charles R Greathouse IV_, Aug 03 2023 %p A302491 map(ithprime, select(numtheory:-issqrfree, [$1..500])); # _Robert Israel_, Nov 06 2023 %t A302491 Prime/@Select[Range[100],SquareFreeQ] %o A302491 (PARI) forprime(p=1, 500, if(issquarefree(primepi(p)), print1(p, ", "))) \\ _Felix Fröhlich_, Apr 10 2018 %o A302491 (PARI) list(lim)=my(v=List(),k); forprime(p=2,lim\1, if(issquarefree(k++), listput(v,p))); Vec(v) \\ _Charles R Greathouse IV_, Aug 03 2023 %Y A302491 Cf. A000040, A000961, A001222, A005117, A007097, A056239, A063834, A275024, A281113, A302242, A302478. %K A302491 nonn,easy %O A302491 1,1 %A A302491 _Gus Wiseman_, Apr 08 2018