Number of meaningful differential operations of the n-th order on the space R^(2+n).

Terms

a(0) =3a(1) =6a(2) =16a(3) =26a(4) =84a(5) =126a(6) =424a(7) =610a(8) =2068a(9) =2936a(10) =9816a(11) =13884a(12) =45608a(13) =64750a(14) =208336a(15) =297570a(16) =938676a(17) =1351492a(18) =4181752a(19) =6071028a(20) =18454648a(21) =27023598a(22) =80796336a(23) =119300636a(24) =351331464a(25) =522981328a(26) =1518742384a(27) =2278188504a(28) =6531607248a(29) =9869753934