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 A113520 #15 May 12 2019 12:39:17
%S A113520 0,1,1,1,4,1,6,1,8,9,10,1,12,9,14,15,16,1,18,9,20,21,22,1,24,25,26,27,
%T A113520 28,1,30,27,32,33,34,35,36,35,38,39,40,25,42,39,44,45,46,35,48,49,50,
%U A113520 51,52,49,54,55,56,57,58,49,60,57,62,63,64,65,66,65,68,69,70,65,72,69,74
%N A113520 a(n) = largest nonprime nonnegative integer < n which is coprime to n.
%C A113520 a(1) = 0 because 0 is coprime with 1, for our purposes and is < 1.
%C A113520 The numbers n with a(n) = 1 are given in A048597. - _Stefan Steinerberger_, Oct 16 2007
%H A113520 Diana Mecum, <a href="/A113520/b113520.txt">Table of n, a(n) for n = 1..1163</a> [From _Diana L. Mecum_, Aug 05 2008]
%e A113520 a(14) = 9 because 9 is the largest nonprime integer < 14 which is coprime to 14 (since the other nonprime integers > 9 and < 14 {10 and 12} aren't coprime with 14).
%t A113520 a = {0}; For[n = 2, n < 70, n++, i = n - 1; While[PrimeQ[i] || GCD[n, i] > 1, i-- ]; AppendTo[a, i]]; a (* _Stefan Steinerberger_, Oct 16 2007 *)
%t A113520 lnp[n_]:=Module[{k=n-1},While[PrimeQ[k]||!CoprimeQ[k,n],k--];k]; Array[ lnp,80] (* _Harvey P. Dale_, May 12 2019 *)
%K A113520 nonn
%O A113520 1,5
%A A113520 _Leroy Quet_, Jan 12 2006
%E A113520 More terms from _Stefan Steinerberger_, Oct 16 2007
%E A113520 Terms 70 through 1163 from _Diana L. Mecum_, Aug 05 2008