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 A284928 #10 Dec 23 2024 14:53:45 %S A284928 0,1,2,3,14,19,26,29,31,34,37,40,41,44,47,49,56,59,61,62,64,68,73,74, %T A284928 76,79,82,83,86,89,91,92,94,95,103,104,106,107,109,110,112,119,121, %U A284928 122,124,125,128,131,134,139,142,145,146,148,149,151,152,154,158,160,161,163,164,166,169 %N A284928 Numbers k such that 2k + p is composite for all primes p, q with p + q = 2k. %C A284928 Or, numbers k such that there is no prime p < 2k with 2k - p and 2k + p both prime. %C A284928 The two initial terms vacuously satisfy the definition, but all even numbers >= 4 are the sum of two primes, according to the Goldbach conjecture. %C A284928 See also A284919, twice this sequence, which lists the values of 2k. %H A284928 Claudio Meller and others, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2017-April/017433.html">New sequence</a>, SeqFan list, April 5, 2017. (Click "next" for subsequent contributions.) %o A284928 (PARI) is_A284928(n)=!forprime(p=2,n, isprime(2*n-p) && (isprime(2*n+p) || isprime(4*n-p)) && return) \\ _M. F. Hasler_, Apr 06 2017 %Y A284928 Cf. A284919 (twice this), A002375 (number of decompositions p + q = 2k), A020481 (least p: p + q = 2k). %K A284928 nonn %O A284928 1,3 %A A284928 _M. F. Hasler_, Apr 06 2017