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 A176897 #13 Jan 16 2025 02:38:21 %S A176897 2,7,11,17,19,23,29,31,41,43,47,53,59,67,71,79,83,89,97,101,103,107, %T A176897 109,113,127,131,137,139,149,151,163,167,173,179,181,191,197,199,211, %U A176897 223,227,229,233,239,241,251,257,263,269,271,281,283,293,307,311,317,331 %N A176897 Primes p such that (p+1)/2 is not a prime. %C A176897 Primes not in A005383. 2 together with A034849. %C A176897 The Ramanujan primes, A104272, are a subsequence. %H A176897 Amiram Eldar, <a href="/A176897/b176897.txt">Table of n, a(n) for n = 1..10000</a> %t A176897 Select[Prime[Range[100]], ! PrimeQ[(#+1)/2] &] %o A176897 (PARI) is(p) = isprime(p) && (p == 2 || !isprime((p+1)/2)); \\ _Amiram Eldar_, Jan 16 2025 %Y A176897 Cf. A005383, A034849, A104272. %K A176897 nonn %O A176897 1,1 %A A176897 _Juri-Stepan Gerasimov_, Apr 28 2010 %E A176897 Entries checked by _R. J. Mathar_, May 01 2010