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 A377514 #7 Jun 21 2025 19:59:52
%S A377514 1,3,1,2,1,1,1,3,1,3,1,1,1,1,2,1,3,2,1,1,1,1,2,1,2,1,1,1,1,2,1,1,3,1,
%T A377514 1,1,1,1,1,3,1,1,1,2,1,1,1,1,1,1,1,1,1,1,3,1,1,1,2,1,3,1,1,1,1,2,1,1,
%U A377514 4,3,2,1,1,3,1,2,1,1,1,2,1,1,1,2,1,3
%N A377514 a(n) = number of iterations of x -> 2 x - 7 to reach a nonprime, starting with prime(n+4).
%C A377514 See A377120 for a guide to related sequences.
%e A377514 prime(6) = 13 -> 19 -> 31 -> 55 = 5*11, so a(2) = 3.
%t A377514 Table[p = Prime[n + 4]; c = 1; While[p = 2*p - 7; PrimeQ[p], c++]; c, {n, 200}]
%Y A377514 Cf. A377120, A377510, A377511, A377512, A377513.
%K A377514 nonn
%O A377514 1,2
%A A377514 _Clark Kimberling_, Nov 05 2024