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 A249110 #24 Feb 18 2021 00:19:34 %S A249110 4,27,3125,398747,823543 %N A249110 Numbers that form a Pythagorean 10-tuple with their first eight arithmetic derivatives. %e A249110 First eight arithmetic derivatives of 398747 are 1692, 2856, 5812, 5816, 8732, 9116, 9500, 15700 and sqrt(398747^2 + 1692^2 + 2856^2 + 5812^2 + 5816^2 + 8732^2 + 9116^2 + 9500^2 + 15700^2) = 399467. %p A249110 with(numtheory); %p A249110 Dr:=proc(w) local x,p; x:=w*add(op(2,p)/op(1,p),p=ifactors(w)[2]); end: %p A249110 P:=proc(q,h) local a,b,k,n; for n from 2 to q do a:=n; b:=n^2; %p A249110 for k from 1 to h do a:=Dr(a); b:=b+a^2; od; if type(sqrt(b),integer) then print(n); %p A249110 fi; od; end: P(10^9,8); %Y A249110 A051674 is a subsequence. - _Ray Chandler_, Dec 22 2016 %Y A249110 Cf. A003415, A051674, A210503, A230543, A249105, A249106, A249107. %K A249110 nonn,more %O A249110 1,1 %A A249110 _Paolo P. Lava_, Oct 21 2014