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 A116509 #6 Aug 01 2021 13:30:28
%S A116509 41,109,221,629,1285,3665,7489,21361,43649,124501,254405,725645,
%T A116509 1482781,4229369,8642281,24650569,50370905,143674045,293583149,
%U A116509 837393701,1711127989,4880688161,9973184785,28446735265,58127980721
%N A116509 Values of c in a^2 + b^2 = c^2 where b - a = 31 and gcd(a,b)=1.
%C A116509 b - a = 31 is the fifth term of A058529
%F A116509 c(1)=41,c(2)=109,c(3)=221,c(4)=629,c(n)=6*c(n-2)-c(n-4)
%e A116509 c(5)= 6*221-41=1285 and 893^2 + 924^2 = 1285^2 and 924-893=31 and gcd(893,924)=1
%t A116509 RecurrenceTable[{a[1]==41,a[2]==109,a[3]==221,a[4]==629,a[n]==6a[n-2]-a[n-4]},a,{n,30}] (* _Harvey P. Dale_, Aug 01 2021 *)
%K A116509 nonn
%O A116509 1,1
%A A116509 Andras Erszegi (erszegi.andras(AT)chello.hu), Mar 21 2006