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 A088631 #11 Aug 03 2021 18:45:42 %S A088631 1,2,3,2,5,6,5,8,9,8,11,10,9,14,15,14,13,18,17,20,21,20,23,22,21,26, %T A088631 25,24,29,30,29,28,33,32,35,36,35,34,39,38,41,40,39,44,43,42,41,48,47, %U A088631 50,51,50,53,54,53,56,55,54,53,52,51,50,63,62,65,64,63,68,69,68,67,66,65,74,75 %N A088631 Largest number m < n such that m+n is a prime. %H A088631 Reinhard Zumkeller, <a href="/A088631/b088631.txt">Table of n, a(n) for n = 2..10000</a> %F A088631 a(n) = p-n where p = largest prime <= 2n-1. %F A088631 a(n) = A060265(n) - n. - _Reinhard Zumkeller_, Feb 22 2015 %e A088631 Adding 1,2,3,2,5 to 2,3,4,5,6 we get the primes 3,5,7,7,11. %p A088631 with(numtheory); A088631 := n->prevprime(2*n)-n; %o A088631 (Haskell) %o A088631 a088631 n = a060265 n - n -- _Reinhard Zumkeller_, Feb 22 2015 %Y A088631 Cf. A088633. Second column of A088643. %Y A088631 Cf. A010051, A060265, A007917. %K A088631 easy,nonn %O A088631 2,2 %A A088631 _N. J. A. Sloane_, Nov 24 2003