Number of permutations on 1..n where gcd(s_i,n) = gcd(i,n). Also Product_{d divides n} phi(d)!.
A120065
Number of permutations on 1..n where gcd(s_i,n) = gcd(i,n). Also Product_{d divides n} phi(d)!.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =2a(4) =24a(5) =4a(6) =720a(7) =48a(8) =1440a(9) =576a(10) =3628800a(11) =192a(12) =479001600a(13) =518400a(14) =1935360a(15) =1935360a(17) =2073600a(19) =46448640a(20) =689762304000a(23) =185794560
External references
- oeis: A120065