Number of Schur rings over Z_{5^n}.

Terms

a(0) =1a(1) =3a(2) =13a(3) =58a(4) =263a(5) =1203a(6) =5531a(7) =25511a(8) =117910a(9) =545730a(10) =2528263a(11) =11720917a(12) =54364253a(13) =252243996a(14) =1170694877a(15) =5434421231a(16) =25230661483a(17) =117153235821a(18) =544024844668