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