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 A342365 #10 Mar 09 2021 08:41:48 %S A342365 3,17,73,337,191,709,1289,3137,3313,3181,7349,5449,8243,11621,7681, %T A342365 16673,17477,28657,27893,74441,71023,87869,94439,33889,250301,298013, %U A342365 205957,131489,327179,87961,1178993,354689,1769791,595817,1304591,417169,2343359 %N A342365 The primes associated with A239800 (1 if A239800(n) = 0). %H A342365 Jianing Song, <a href="/A342365/b342365.txt">Table of n, a(n) for n = 1..100</a> %F A342365 a(n) = 2*n*A239800(n)+1. %e A342365 The smallest m such that 2*m*i + 1 is not prime until i = 3 is m = 12, and the corresponding prime is 2*12*3 + 1 = 73 = a(3). %e A342365 The smallest m such that 2*m*i + 1 is not prime until i = 4 is m = 42, and the corresponding prime is 2*42*4 + 1 = 337 = a(4). %e A342365 The smallest m such that 2*m*i + 1 is not prime until i = 5 is m = 19, and the corresponding prime is 2*19*5 + 1 = 191 = a(5). %o A342365 (PARI) isok(n, m) = for(i=1, n-1, if(isprime(2*m*i+1), return(0))); if(isprime(2*m*n+1), 1, 0) %o A342365 a(n) = for(m=1, oo, if(isok(n, m), return(2*n*m+1))) \\ based on the conjecture that all numbers occur in A016014 %Y A342365 Cf. A239800, A016014, A070846, A342364. %K A342365 nonn %O A342365 1,1 %A A342365 _Jianing Song_, Mar 09 2021