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 A129471 #3 Mar 31 2012 13:48:24
%S A129471 883,1747,2417,2621,3301,3533,3571,3691,3853,4027,4133,4783,4861,5303,
%T A129471 5381,5393,5563,5641,5821,6577,6991,7253,7331,8059,8093,8377,8839,
%U A129471 8929,8969,9221,9281,9613,9931,10069,10477,10487,10601,10607,10903,11491
%N A129471 Primes p of Erdos-Selfridge class 3+ with largest prime factor of p+1 not of class 2+.
%C A129471 See A129470
%e A129471 a(1) = 883 = -1+2*13*17 is a prime of class 3+ since 13 is of class 2+, but the largest divisor of 883+1 is 17 which is only of class 1+.
%o A129471 (PARI) class(n,s=1)={n=factor(n+s)[,1];if(n[ #n]<=3,1,for(i=2,#n,n[1]=max(class(n[i],s)+1,n[1]));n[1])}; A129471(n=100,p=1,a=[])={ local(f); while( #a<n, until( f[ #f] > 3 & 2 > class(f[ #f]), f=factor(1+p=nextprime(p+1))[,1]); forstep( i=#f-1,2,-1, if( 3 < f[1] = max( f[1],1+class( f[i] )), next(2))); if( f[1] == 3, a=concat(a,p); /*print(#a," ",p)*/)); a}
%Y A129471 Subsequence of A129470; see also A129472-A129473, A129477-A129478, A129469, A005113, A005105-A005107.
%K A129471 easy,nonn
%O A129471 1,1
%A A129471 _M. F. Hasler_, Apr 17 2007