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 A249106 #27 Feb 18 2021 00:19:18 %S A249106 19164,129357,14971875,45316123,434325391 %N A249106 Numbers that form a Pythagorean 6-tuple with their first four arithmetic derivatives. %e A249106 First four arithmetic derivatives of 19164 are 25564, 31848, 58412, 61916 and sqrt(19164^2 + 25564^2 + 31848^2 + 58412^2 + 61916^2) = 96336. %p A249106 with(numtheory); %p A249106 Dr:=proc(w) local x,p; x:=w*add(op(2,p)/op(1,p),p=ifactors(w)[2]); end: %p A249106 P:=proc(q,h) local a,b,k,n; for n from 2 to q do a:=n; b:=n^2; %p A249106 for k from 1 to h do a:=Dr(a); b:=b+a^2; od; if type(sqrt(b),integer) then print(n); %p A249106 fi; od; end: P(10^9,4); %Y A249106 Cf. A003415, A210503, A230543, A249105, A249107, A249110. %K A249106 nonn,more %O A249106 1,1 %A A249106 _Paolo P. Lava_, Oct 21 2014 %E A249106 a(4) from _Ray Chandler_, Dec 23 2016 %E A249106 a(5) from _Ray Chandler_, Jan 11 2017