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 A377513 #4 Nov 13 2024 17:26:27
%S A377513 8,1,7,1,2,6,1,1,1,1,3,5,2,1,1,3,1,1,1,2,1,4,1,1,1,1,1,4,2,1,2,1,1,1,
%T A377513 1,1,3,1,1,1,3,1,1,1,2,1,2,1,1,1,3,2,1,1,1,7,1,1,1,3,1,1,1,1,1,1,2,1,
%U A377513 1,1,1,2,2,1,2,1,1,1,4,1,1,2,1,1,1,1
%N A377513 a(n) = number of iterations of x -> 2 x - 5 to reach a nonprime, starting with prime(n+4).
%C A377513 See A377120 for a guide to related sequences.
%e A377513 prime(5) = 11 -> 17 -> 29 -> 53 -> 101 -> 197 -> 389 -> 773 -> 1541 = 23*67,
%e A377513 so a(1) = 8.
%t A377513 Table[p = Prime[n + 4]; c = 1; While[p = 2*p - 5; PrimeQ[p], c++]; c, {n, 200}]
%Y A377513 Cf. A377120, A377510, A377511, A377512, A377514.
%K A377513 nonn
%O A377513 1,1
%A A377513 _Clark Kimberling_, Nov 05 2024