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 A302493 #7 Apr 10 2018 21:47:57 %S A302493 2,3,5,7,11,17,19,23,31,41,53,59,67,83,97,103,109,127,131,157,179,191, %T A302493 211,227,241,277,283,311,331,353,367,401,419,431,461,509,547,563,587, %U A302493 599,617,661,691,709,719,739,773,797,859,877,919,967,991,1009,1031 %N A302493 Prime numbers of prime-power index. %C A302493 A prime index of n is a number m such that prime(m) divides n. %F A302493 a(n) = A000040(A000961(n)). %t A302493 Prime/@Select[Range[100],Or[#===1,PrimePowerQ[#]]&] %o A302493 (PARI) forprime(p=1, 500, if(p==2 || isprimepower(primepi(p)), print1(p, ", "))) \\ _Felix Fröhlich_, Apr 10 2018 %Y A302493 Cf. A000040, A000961, A001222, A005117, A007097, A056239, A063834, A275024, A281113, A302242, A302491, A302492. %K A302493 nonn %O A302493 1,1 %A A302493 _Gus Wiseman_, Apr 08 2018