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 A306627 #22 Nov 17 2024 14:08:53 %S A306627 43,53,79,97,199,257,347,1103,1187,1303,1367,1753,2029,2351,2593,2647, %T A306627 3181,3253,4663,4787,4903,4919,5573,6091,7079,7331,7369,7457,8101, %U A306627 8527,8543,10159,11549,12647,13151,14699,15031,15559,15679,15881,15889,16661,17099,17881,18251,18959,19219,20399,20431 %N A306627 Primes of the form (p + prime(p))/2 with prime p. %C A306627 Indices k of p's are 8, 9, 11, 12, 19, 23, 28, 62, 64, 68, 71, 85, 95, 104, 114, 115, 131, 134, 175, 178, 181, 182, 200, 216, 240, 246, 247, 250, 266, 276, 277, 316, 346, 372, 382. %C A306627 And some of k's themselves are prime: 11, 19, 23, 71, 131, 181, 277, 421, 541, 601, 673, 751, 881, 937. See link to Fernandez. %H A306627 Neil Fernandez, <a href="http://www.borve.org/primeness/FOP.html">An order of primeness</a>. %e A306627 43 = (p + prime(p))/2 for p = 19 (prime), %e A306627 53 = (p + prime(p))/2 for p = 23 (prime). %o A306627 (PARI) lista(nn) = forprime(p=3,nn,k=(prime(p)+p)/2;if(isprime(k),print1(k, ", "))) \\ _Jinyuan Wang_, Mar 01 2019 %Y A306627 Cf. A014688 (n-th prime + n). %K A306627 nonn %O A306627 1,1 %A A306627 _Zak Seidov_, Mar 01 2019