Dimension of 4-variable non-commutative harmonics (twisted derivative). The dimension of the space of non-commutative polynomials in 4 variables which are killed by all symmetric differential operators (where for a monomial w, d_{xi} ( xi w ) = w and d_{xi} ( xj w ) = 0 for i/=j).
A122368
Dimension of 4-variable non-commutative harmonics (twisted derivative). The dimension of the space of non-commutative polynomials in 4 variables which are killed by all symmetric differential operators (where for a monomial w, d_{xi} ( xi w ) = w and d_{xi} ( xj w ) = 0 for i/=j).
Terms
- a(0) =1a(1) =3a(2) =11a(3) =42a(4) =162a(5) =627a(6) =2430a(7) =9423a(8) =36549a(9) =141777a(10) =549990a(11) =2133594a(12) =8276985a(13) =32109534a(14) =124565121a(15) =483235875a(16) =1874657763a(17) =7272519066a(18) =28212902154a(19) =109448714619a(20) =424593725526
External references
- oeis: A122368