Non-squarefree elements of A003824, i.e., primitive solutions to a^4 + b^4 = c^4 + d^4 with non-squarefree value on both sides of the equation.
680914892583617, 55683917506335026, 2056314197022256097
1 seqfan posts
Tue Mar 6 05:49:05 CET 2012 [seqfan] A088867 and A003824: solutions to a^4+b^4=c^4+d^4