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 A360081 #21 Jan 27 2023 15:26:59
%S A360081 3,19,31,691,907,2887,15943,69283,216127,1108831,8344423,10976347,
%T A360081 166965391,385465771,26580643
%N A360081 Smallest k such that 2^(3*2^n) + k is a safe prime.
%C A360081 a(n) == 3 (mod 4). - _Chai Wah Wu_, Jan 27 2023
%F A360081 a(n) = A350696(3*2^n).
%e A360081 a(1) = 19 because 2^(3*2^1)+19 = 2^6+19 = 83 is the smallest safe prime greater than 64.
%o A360081 (PARI) a(n) = {my(k=1); pow2 = 2^(3*2^n); while (!(isprime(pow2 + k) && isprime((pow2 + k - 1)/2)), k+=2); k;} \\
%o A360081 (Python)
%o A360081 from sympy import isprime, nextprime
%o A360081 def A360081(n):
%o A360081 m = 1<<3*(1<<n)-1
%o A360081 i = m
%o A360081 while i:=nextprime(i):
%o A360081 if isprime(k:=(i<<1)+1):
%o A360081 return k-(m<<1) # _Chai Wah Wu_, Jan 27 2023
%Y A360081 Cf. A360080, A335313, A350696, A005385, A013597, A013603, A181356, A057821.
%K A360081 nonn,more,hard
%O A360081 0,1
%A A360081 _Mark Andreas_, Jan 25 2023