Rank of the inverse semigroup D_n of all difunctional relations on an n-element set.
A294431
Rank of the inverse semigroup D_n of all difunctional relations on an n-element set.
Terms
- a(0) =1a(1) =2a(2) =3a(3) =8a(4) =19a(5) =57a(6) =209a(7) =884a(8) =4148a(9) =21156a(10) =115985a(11) =678581a(12) =4213609a(13) =27644450a(14) =190899336a(15) =1382958560a(16) =10480142163a(17) =82864869821a(18) =682076806177
External references
- oeis: A294431