Primal codes of finite idempotent functions on positive integers.

Terms

a(0) =1a(1) =2a(2) =9a(3) =18a(4) =125a(5) =250a(6) =1125a(7) =2250a(8) =2401a(9) =4802a(10) =21609a(11) =43218a(12) =161051a(13) =300125a(14) =322102a(15) =600250a(16) =1449459a(17) =2701125a(18) =2898918a(19) =4826809a(20) =5402250a(21) =9653618a(22) =20131375a(23) =40262750a(24) =43441281a(25) =86882562a(26) =181182375a(27) =362364750a(28) =386683451a(29) =410338673