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 A342691 #41 Aug 16 2024 21:20:20 %S A342691 7,13,31,73,307,757,1723,3541,5113,8011,10303,17293,28057,30103,86143, %T A342691 147073,262657,459007,492103,552793,579883,598303,684757,704761, %U A342691 735307,830833,1191373,1204507,1353733,1395943,1424443,1482307,1772893,1886503,2037757,2212657 %N A342691 Primes of the form (p^k)^2 + p^k + 1 with prime p and positive integer k. %C A342691 Also, primes of the form (p^3^m)^2 + p^3^m + 1 with prime p and nonnegative integer m, since k must be a power of 3, from the theory of cyclotomic polynomials. %H A342691 Martin Becker, <a href="/A342691/b342691.txt">Table of n, a(n) for n = 1..20000</a> %e A342691 31 = (5^1)^2 + 5^1 + 1 is in the sequence as 31 is prime and 5 is prime and 1 is a positive integer. %e A342691 73 = (2^3)^2 + 2^3 + 1 is in the sequence as it is prime and 2 is prime and 3 is a positive integer. %t A342691 Select[Table[q^2 + q + 1, {q, Select[Range[1500], PrimePowerQ[#] &]}], PrimeQ] (* _Amiram Eldar_, Aug 16 2024 *) %o A342691 (PARI) for(q=2,2048,if(isprimepower(q),m=q^2+q+1;if(isprime(m),print1(m, ", ")))) %Y A342691 Contains A053183 and A063784. %Y A342691 Intersection of A335865 and A000040 minus {3}. %Y A342691 Cf. A342690, A344448. %K A342691 nonn %O A342691 1,1 %A A342691 _Martin Becker_, May 18 2021