A249106 - OEIS

%I #27 Feb 18 2021 00:19:18

%S 19164,129357,14971875,45316123,434325391

%N Numbers that form a Pythagorean 6-tuple with their first four arithmetic derivatives.

%e 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 with(numtheory);

%p Dr:=proc(w) local x,p; x:=w*add(op(2,p)/op(1,p),p=ifactors(w)[2]); end:

%p P:=proc(q,h) local a,b,k,n; for n from 2 to q do a:=n; b:=n^2;

%p for k from 1 to h do a:=Dr(a); b:=b+a^2; od; if type(sqrt(b),integer) then print(n);

%p fi; od; end: P(10^9,4);

%Y Cf. A003415, A210503, A230543, A249105, A249107, A249110.

%K nonn,more

%O 1,1

%A _Paolo P. Lava_, Oct 21 2014

%E a(4) from _Ray Chandler_, Dec 23 2016

%E a(5) from _Ray Chandler_, Jan 11 2017