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 A381313 #8 Feb 21 2025 08:13:27 %S A381313 27,54,81,108,125,135,162,189,216,243,250,270,297,324,343,351,375,378, %T A381313 405,432,459,486,500,513,540,567,594,621,625,648,675,686,702,729,750, %U A381313 756,783,810,837,864,875,891,918,945,972,999,1000,1026,1029,1053,1080,1107,1125 %N A381313 Numbers that are divisible by the cube of an odd prime. %C A381313 Numbers whose odd part is not cubefree. %C A381313 The asymptotic density of this sequence is 1 - 8/(7*zeta(3)) = 1 - 1/A233091 = 0.04924871705062003579... . %H A381313 Amiram Eldar, <a href="/A381313/b381313.txt">Table of n, a(n) for n = 1..10000</a> %t A381313 cubeFreeQ[k_] := Max[FactorInteger[k][[;;, 2]]] < 3; q[k_] := !cubeFreeQ[k / 2^IntegerExponent[k, 2]]; Select[Range[1200], q] %o A381313 (PARI) iscubefree(k) = if(k == 1, 1, vecmax(factor(k)[, 2]) < 3); %o A381313 isok(k) = !iscubefree(k >> valuation(k, 2)); %Y A381313 Subsequence of A046099 and A038838. %Y A381313 Cf. A000265, A002117, A233091. %K A381313 nonn,easy %O A381313 1,1 %A A381313 _Amiram Eldar_, Feb 19 2025