a(n) = Sum_{0 < x,y,z,t <= n and gcd(x^2 + y^2 + z^2 + t^2, n)=1} gcd(x^2 + y^2 + z^2 + t^2 - 1, n).
A239613
a(n) = Sum_{0 < x,y,z,t <= n and gcd(x^2 + y^2 + z^2 + t^2, n)=1} gcd(x^2 + y^2 + z^2 + t^2 - 1, n).
Terms
- a(0) =1a(1) =16a(2) =96a(3) =384a(4) =960a(5) =1536a(6) =4032a(7) =8192a(8) =11664a(9) =15360a(10) =26400a(11) =36864a(12) =52416a(13) =64512a(14) =92160a(15) =163840a(16) =156672a(17) =186624a(18) =246240a(19) =368640a(20) =387072a(21) =422400a(22) =534336a(23) =786432a(24) =900000a(25) =838656a(26) =1259712a(27) =1548288a(28) =1364160a(29) =1474560
External references
- oeis: A239613