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 A272601 #13 Feb 16 2024 01:29:20 %S A272601 4,6,8,10,12,14,15,16,18,20,22,24,26,27,28,30,32,34,35,36,38,39,40,42, %T A272601 44,45,46,48,50,51,52,54,56,57,58,60,62,63,64,66,68,69,70,72,74,75,76, %U A272601 77,78,80,82,84,86,87,88,90,91,92,93,94,95,96,98,99,100,102,104,105,106,108,110,111,112,114,115,116 %N A272601 Composites n such that p-1 does not divide n-1 for at least one prime divisor of n-1. %C A272601 Composites not in A272600. %H A272601 Charles R Greathouse IV, <a href="/A272601/b272601.txt">Table of n, a(n) for n = 1..10000</a> %o A272601 (PARI) forcomposite(n=4, 10^3, my(q=1, f=factor(n-1)[,1]); for(j=1, #f, if((n-1)%(f[j]-1), q=0; break)); if(!q, print1(n,", "))); %K A272601 nonn %O A272601 1,1 %A A272601 _Joerg Arndt_, May 16 2016