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 A377364 #5 Nov 04 2024 22:29:09
%S A377364 1,1,1,2,1,1,1,3,2,1,1,1,1,3,2,1,1,1,4,5,1,2,1,2,1,1,1,9,2,1,4,1,1,2,
%T A377364 1,5,1,1,11,1,2,2,4,3,1,1,1,3,2,4,1,1,5,3,1,1,3,1,2,4,1,1,1,2,2,1,5,1,
%U A377364 3,1,2,1,1,8,3,1,1,4,2,80,1,6,1,8,2,2
%N A377364 a(n) = least k such that 2n*3^k-2 is prime, or 0 if no prime is reached.
%e A377364 a(20) = 5 because 40*3^5 + 1 is prime and 40*3^k + 1 is not prime for k=1..4.
%t A377364 {b, h} = {3, 2}; f[n_, k_] := n*b^k - h
%t A377364 s[n_] := Select[Range[20], PrimeQ[f[n, #]] &, 1]
%t A377364 Flatten[Table[s[n], {n, 1, 200}]]
%Y A377364 Cf. A000040, A050412, A354747, A377365, A377366, A377367.
%K A377364 nonn
%O A377364 1,4
%A A377364 _Clark Kimberling_, Oct 31 2024