Number of distinct sums of n complex n-th roots of 1.

Terms

a(0) =1a(1) =3a(2) =10a(3) =25a(4) =126a(5) =127a(6) =1716a(7) =2241a(8) =18469a(9) =15231a(10) =352716a(11) =36973a(12) =5200300a(13) =1799995a(14) =30333601a(15) =24331777a(16) =1166803110a(17) =12247363a(18) =17672631900a(19) =723276561