The number of set partitions of {1,2,...,n} into exactly two subsets A,B such that the greatest common divisor of |A| and |B| = 1.

A194924

The number of set partitions of {1,2,...,n} into exactly two subsets A,B such that the greatest common divisor of |A| and |B| = 1.

Terms

    a(0) =1a(1) =3a(2) =4a(3) =15a(4) =6a(5) =63a(6) =64a(7) =171a(8) =130a(9) =1023a(10) =804a(11) =4095a(12) =2380a(13) =7920a(14) =16384a(15) =65535a(16) =40410a(17) =262143a(18) =246640a(19) =582771a(20) =695860a(21) =4194303a(22) =2884776a(23) =13455325a(24) =11576916a(25) =44739243a(26) =65924824a(27) =268435455a(28) =176422980a(29) =1073741823

External references