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 A278932 #14 Dec 07 2016 12:36:36 %S A278932 1122659,2164229,2329469,10257809,10309889,12314699,14030309,14145539, %T A278932 19099919,23103659,24176129,28843649,37088729,38199839,42389519, %U A278932 49160099,50785439,52554569,62800169,68718059,85864769,88174049,95831189,105109139,105388169 %N A278932 Numbers n such that n remains prime through 6 iterations of function f(x) = 2x + 1. %C A278932 n, 2*n+1, 4*n+3, 8*n+7, 16*n+15, 32*n+31, and 64*n+63 are primes. %C A278932 a(n) == 29 (mod 30). %o A278932 (PARI) a005408(n) = 2*n+1 %o A278932 count(n) = my(k=n, i=0); while(ispseudoprime(k), k=a005408(k); i++); i %o A278932 is(n) = count(n) > 6 \\ _Felix Fröhlich_, Dec 05 2016 %Y A278932 Subsequence of A007700, A023272, A023302, and A023330. %K A278932 nonn %O A278932 1,1 %A A278932 _John Cerkan_, Dec 01 2016