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 A246120 #23 Jan 01 2023 09:44:11
%S A246120 2,6,7,93,15,372,421,759,7426,9087
%N A246120 Least k such that k^(3^n)*(k^(3^n) - 1) + 1 is prime.
%C A246120 Numbers of the form k^m*(k^m - 1) + 1 with m > 0, k > 1 may be primes only if m is 3-smooth, because these numbers are Phi(6,k^m) and cyclotomic factorizations apply to any prime divisors > 3. This sequence is a subset of A205506 with only m=3^n, which is similar to A153438.
%C A246120 Search limits: a(10) > 35000, a(11) > 3500.
%F A246120 a(n) = A085398(2*3^(n+1)). - _Jinyuan Wang_, Jan 01 2023
%e A246120 When k = 7, k^18 - k^9 + 1 is prime. Since this isn't prime for k < 7, a(2) = 7.
%t A246120 a246120[n_Integer] := Module[{k = 1},
%t A246120 While[! PrimeQ[k^(3^n)*(k^(3^n) - 1) + 1], k++]; k]; a246120 /@ Range[0, 9] (* _Michael De Vlieger_, Aug 15 2014 *)
%o A246120 (PARI)
%o A246120 a(n)=k=1;while(!ispseudoprime(k^(3^n)*(k^(3^n)-1)+1),k++);k
%o A246120 n=0;while(n<100,print1(a(n),", ");n++) \\ _Derek Orr_, Aug 14 2014
%Y A246120 Cf. A056993, A085398, A101406, A153436, A153438, A205506, A246119, A246121.
%K A246120 nonn,more,hard
%O A246120 0,1
%A A246120 _Serge Batalov_, Aug 14 2014