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 A238445 #13 Jun 26 2020 05:32:35 %S A238445 3,13,61,103,193,199,307,431,569,977,1201,1451,1481,1609,1669,1889, %T A238445 2371,2381,2711,2819,3083,3469,4289,4337,4567,5231,5501,6733,7043, %U A238445 7253,7351,7549,8707,9257,9497,10039,10687,11491,12227,12517,12941,13397 %N A238445 Primes p such that f(f(p)) is prime, where f(x) = x^5-x^4-x^3-x^2-x-1. %e A238445 3 is prime. 3^5-3^4-3^3-3^2-3-1 = 122 and 122^5-122^4-122^3-122^2-122-1 = 26803717321 is a prime number. Thus, 3 is a member of this sequence. %o A238445 (Python) %o A238445 import sympy %o A238445 from sympy import isprime, primerange %o A238445 def f(x): %o A238445 return x**5-x**4-x**3-x**2-x-1 %o A238445 [p for p in primerange(2, 10**5) if isprime(f(f(p)))] %Y A238445 Cf. A125083, A237640. %K A238445 nonn %O A238445 1,1 %A A238445 _Derek Orr_, Feb 26 2014