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 A152769 #7 May 06 2019 17:56:54 %S A152769 1,2,7,8,9,10,13,14,15,16,19,20,21,22,23,24,25,26,27,28,29,30,37,38, %T A152769 39,40,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,61,62,63,64,65, %U A152769 66,71,72,73,74,75,76,77,78,79,80,81,82,89,90,91,92,93,94,95,96,97,98,99 %N A152769 Numbers n such that pi(n) is nonprime. %C A152769 A000720(n) is nonprime. %C A152769 Complement of A048989. %H A152769 Omar E. Pol, <a href="http://www.polprimos.com/imagenespub/polprdipi.jpg"> Divisors and pi(x)</a> %t A152769 Select[Range[100],!PrimeQ[PrimePi[#]]&] (* _Harvey P. Dale_, May 06 2019 *) %Y A152769 Cf. A000720, A048989, A141468. %K A152769 easy,nonn %O A152769 1,2 %A A152769 _Omar E. Pol_, Dec 18 2008 %E A152769 Edited by _N. J. A. Sloane_, Dec 19 2008