cp's OEIS Frontend

A211176 Numbers n which are the hypotenuse of a Pythagorean triple with n' as a leg, where n' is the arithmetic derivative of n.

%I A211176 #26 Jan 28 2017 14:43:43
%S A211176 125,625,23125,142805,210125,371293,7983625,9370805,25757525,50062025,
%T A211176 120670225,489766225,881052625,1471596725,2307267625,2489771125,
%U A211176 3145529225,3474871553,6975757441,7977558641
%N A211176 Numbers n which are the hypotenuse of a Pythagorean triple with n' as a leg, where n' is the arithmetic derivative of n.
%C A211176 This sequence is a subsequence of A008846. - _Ray Chandler_, Jan 27 2017
%F A211176 A002144(n)^A002365(n) and A002144(n)^A002366(n) are terms of the sequence for all n. - _Ray Chandler_, Jan 27 2017
%e A211176 n = 23125, n' = 19125 and sqrt(n^2-n'^2) = 13000.
%p A211176 with(numtheory); ListA211176:= proc(q)local a,n,p;
%p A211176 for n from 2 to q do a:=n*add(op(2,p)/op(1,p),p=ifactors(n)[2]);
%p A211176 if n<>a and type(sqrt(n^2-a^2),integer) then print(n); fi;
%p A211176 od; end: ListA211176(10^9);
%Y A211176 Cf. A002144, A002365, A002366, A003415, A008846, A009003, A009004, A210503.
%K A211176 nonn,more
%O A211176 1,1
%A A211176 _Paolo P. Lava_, Feb 01 2013
%E A211176 Name and Maple program corrected by _Paolo P. Lava_, Sep 30 2013
%E A211176 a(12)-a(16) from _Donovan Johnson_, Sep 30 2013
%E A211176 a(17)-a(18) from _Ray Chandler_, Jan 25 2017
%E A211176 a(19)-a(20) from _Ray Chandler_, Jan 27 2017