5771363domain: NAppears in sequencesa(n) = 1^n + 3^n + 7^n.at n=8A074509a(n) = Sum_{k=0..n} (-1)^(n-k)*C(n,k)*sigma(n,k) for n>0 with a(0)=1.at n=8A163191Sum of the 8th powers of the odd proper divisors of n.at n=20A352036