A147856 - OEIS

%I #5 Jul 23 2022 22:13:12

%S 520,975,2040,3567,7215,7800,9840,13920,19680,30160,40545,53040,57720,

%T 62985,95120,108225,138040,151320,180960,230880,247520,286200,289952,

%U 352495,473280,535353,546975,720945,769600,1048560,1141920,1210560

%N Positive integers n such that n^2 = (x^4 - y^4)*(z^4 - t^4) where x>y and z>t are distinct pairs of integers with gcd(x,y)=gcd(z,t)=1.

%C Positive integers n such that n^2 = A147858(m)*A147858(k) for positive integers k<m. Primitive elements of A147854: any element n of A147854 is of the form a(k)*s^2 for some positive integer s.

%C 4*A196289(2*k) and A196289(2*k+1) belong to this sequence.

%K nonn

%O 1,1

%A _Max Alekseyev_, Nov 18 2008