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 A268064 #37 Sep 18 2024 23:03:02 %S A268064 1,2,3,6,10,15,30,34,35,46,55,62,83,230,1675,2551,3934,25101,28703, %T A268064 46295,54363,72846 %N A268064 Integers k such that (2^k + 1) + (3^k + 1) + (5^k + 1) is prime. %C A268064 Inspired by A268067. %C A268064 Integers k such that A000051(k) + A034472(k) + A034474(k) is a prime number. %C A268064 Corresponding primes are 13, 41, 163, 16421, 9825701, 30531959803, 931322780507684352101, 582076625811872951801381, 2910383095704949820066203, ... %C A268064 a(18) > 10000. - _Tyler NeSmith_, May 07 2021 %e A268064 2 is a term because (2^2 + 1) + (3^2 + 1) + (5^2 + 1) = 41 is prime. %t A268064 Select[Range[0, 2000], PrimeQ[(2^#+1) + (3^#+1) + (5^#+1)] &] (* _Vaclav Kotesovec_, Jan 26 2016 *) %o A268064 (PARI) lista(nn) = for(n=1, nn, if(ispseudoprime(3 + 2^n + 3^n + 5^n), print1(n, ", "))); %Y A268064 Cf. A000051, A034472, A034474, A268067. %K A268064 nonn,hard,more %O A268064 1,2 %A A268064 _Altug Alkan_, Jan 25 2016 %E A268064 a(18)-a(19) from _Michael S. Branicky_, Apr 12 2023 %E A268064 a(20)-a(22) from _Michael S. Branicky_, Sep 18 2024