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 A381793 #28 Mar 16 2025 15:03:15 %S A381793 6,11,649,792,1034,12386,21813,87318,35387,207339,67958 %N A381793 Smallest k>1 such that 10*k^(5*2^n)+1 is prime. %e A381793 a(0) = 6, because 10*6^(5*2^0)+1 equals 77761 which is prime. %o A381793 (Python) %o A381793 from sympy import isprime %o A381793 from itertools import count %o A381793 def a(n): return next(k for k in count(2) if isprime(k**(5*(2**n)) * 10 + 1)) %Y A381793 Cf. A020714, A089319. %Y A381793 Cf. A381815. %K A381793 nonn,base,hard,more %O A381793 0,1 %A A381793 _Jakub Buczak_, Mar 07 2025 %E A381793 a(7)-a(10) from _Michael S. Branicky_, Mar 07 2025