Number of distinct functions f representable as x -> x^x^...^x with n x's and parentheses inserted in all possible ways giving result f(0)=1, with conventions that 0^0=1^0=1^1=1, 0^1=0.
A222380
Number of distinct functions f representable as x -> x^x^...^x with n x's and parentheses inserted in all possible ways giving result f(0)=1, with conventions that 0^0=1^0=1^1=1, 0^1=0.
Terms
- a(0) =0a(1) =0a(2) =1a(3) =1a(4) =3a(5) =5a(6) =14a(7) =29a(8) =77a(9) =179a(10) =472a(11) =1174a(12) =3100a(13) =8018a(14) =21370a(15) =56601a(16) =152337a(17) =409954a(18) =1113501a(19) =3030710a(20) =8298035a(21) =22780468a(22) =62800860a(23) =173586690a(24) =481335403a(25) =1337916253a(26) =3728371645a(27) =10412163861a(28) =29139846448a(29) =81705768401
External references
- oeis: A222380