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 A035031 #17 Dec 15 2023 11:39:08
%S A035031 1,2,2,3,3,5,5,7,7,7,7,11,11,13,13,13,14,17,17,19,19,19,19,23,23,23,
%T A035031 23,23,26,29,29,31,31,31,31,31,34,37,37,37,38,41,41,43,43,43,43,47,47,
%U A035031 47,47,47,47,53,53,53,53,53
%N A035031 For n >= 7, max(A151799(n), 2*A151799(floor((n-1)/2))).
%D A035031 S. K. Stein and S. Szabo, Algebra and Tiling, MAA Carus Monograph 25, 1994, page 104.
%H A035031 Robert Israel, <a href="/A035031/b035031.txt">Table of n, a(n) for n = 1..10000</a>
%p A035031 f:= proc(n) max(prevprime(n), 2*prevprime(floor((n-1)/2))) end proc:
%p A035031 for i from 1 to 6 do f(i):= [1, 2, 2, 3, 3, 5, 5][i] od:
%p A035031 map(f, [$1..100]); # _Robert Israel_, Dec 15 2023
%t A035031 Join[{1,2},Table[Max[NextPrime[n,-1],2NextPrime[Floor[(n-1)/2],-1]],{n,3,70}]] (* _Harvey P. Dale_, Mar 12 2022 *)
%Y A035031 Cf. A035032, A151799.
%K A035031 nonn
%O A035031 1,2
%A A035031 _N. J. A. Sloane_