-19487170domain: ZAppears in sequencesa(n) = 1 - n^7.at n=11A024005a(n) = Sum_{d|n, d==1 mod 4} d^7 - Sum_{d|n, d==3 mod 4} d^7.at n=10A321823a(n) = Sum_{d|n, d==1 mod 4} d^7 - Sum_{d|n, d==3 mod 4} d^7.at n=21A321823