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 A265128 #36 Dec 06 2015 08:02:40 %S A265128 0,1,12,15,18,20,21,24,28,30,33,35,36,39,40,42,44,45,48,50,51,52,54, %T A265128 55,56,57,60,63,65,66,68,69,70,72,75,76,77,78,80,84,85,87,88,90,91,92, %U A265128 93,95,96,98,99,100,102,104,105,108,110,111,112,114,115,116 %N A265128 Nonprimes excluding numbers of the forms 2*p and p^i where p is a prime and i is a positive integer. %t A265128 Select[Range@ 120, And[! PrimeQ@ #, Nand[EvenQ@ #, PrimeQ[#/2]], ! PrimePowerQ@ #] &] (* _Michael De Vlieger_, Dec 02 2015 *) %o A265128 (PARI) isok(n) = ! (isprime(n) || (! (n%2) && isprime(n/2)) || isprimepower(n)); \\ _Michel Marcus_, Dec 02 2015 %Y A265128 Cf. A000961, A024619, A100484, A264828. %K A265128 nonn,easy %O A265128 1,3 %A A265128 _Giovanni Teofilatto_, Dec 02 2015