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 A097349 #4 Mar 30 2012 17:36:43 %S A097349 1,2,13,72,318,13583 %N A097349 Numbers n such that (Sum (2k)^k, k=1..n) + 1 is prime. %C A097349 Some of the larger entries may only correspond to probable primes. %C A097349 The numbers produced by 72 and 318 have now been certified prime by Primo. 13583, found by PrimeForm using recurrence mode, corresponds to a 60228-digit probable prime. - _Rick L. Shepherd_, Apr 29 2006 %e A097349 13 is a term as 2^1 + 4^2 + 6^3 + 8^4 + 10^5 + 12^6 + 14^7 + 16^8 + 18^9 + 20^10 + 22^11 + 24^12 + 26^13 + 1 = 2518267981703965963, which is prime (certified with Primo). %o A097349 (PARI) s=1; for(k=1,700, s=s+(2*k)^k; if(isprime(s), print1(k,","))) %Y A097349 Cf. A073825 (Sum k^k, k=1..n, is prime), A097350 ((Sum (2k)^k, k=1..n) - 1 is prime). %K A097349 more,nonn %O A097349 1,2 %A A097349 _Rick L. Shepherd_, Aug 07 2004 %E A097349 One more term from _Rick L. Shepherd_, Apr 29 2006