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 A204998 #14 Sep 29 2018 18:41:14
%S A204998 3,8,3,8,5,12,7,8,9,20,11,12,13,28,15,16,17,72,19,20,21,44,23,24,75,
%T A204998 52,27,28,29,60,31,32,33,68,35,72,37,76,39,40,41,84,43,44,45,92,47,48,
%U A204998 147,200,51,52,53,108,55,56,57,116,59,60,61,124,63,64,65,132,67,68,69,140,71,72,73,148,75,76,77,156,79,80,81,164
%N A204998 a(n) = k^2 - j^2, where (k^2,j^2) is the least pair of distinct squares for which n divides their difference.
%C A204998 For a guide to related sequences, see A204892.
%H A204998 Antti Karttunen, <a href="/A204998/b204998.txt">Table of n, a(n) for n = 1..23005</a>
%F A204998 a(n) = A204996(n) - A204997(n).
%t A204998 (See the program at A204994.)
%o A204998 (PARI) A204998(n) = { my(d); for(k=sqrtint(1+n), oo, for(j=1,k-1,if(!((d=(k^2)-(j^2))%n),return(d),if(d<n,break)))); }; \\ _Antti Karttunen_, Sep 28 2018
%Y A204998 Cf. A204994, A204892, A204996, A204997, A204999.
%K A204998 nonn
%O A204998 1,1
%A A204998 _Clark Kimberling_, Jan 21 2012
%E A204998 More terms from _Antti Karttunen_, Sep 28 2018