Number of associative, quasitrivial, and order-preserving binary operations on the n-element set {1,...,n}.
A293005
Number of associative, quasitrivial, and order-preserving binary operations on the n-element set {1,...,n}.
Terms
- a(0) =0a(1) =1a(2) =4a(3) =12a(4) =34a(5) =94a(6) =258a(7) =706a(8) =1930a(9) =5274a(10) =14410a(11) =39370a(12) =107562a(13) =293866a(14) =802858a(15) =2193450a(16) =5992618a(17) =16372138a(18) =44729514a(19) =122203306a(20) =333865642a(21) =912137898a(22) =2492007082a(23) =6808289962a(24) =18600594090a(25) =50817768106a(26) =138836724394a(27) =379308985002
External references
- oeis: A293005