Triangle S(n,k) by rows: coefficients of 5^(n/2)*(x^(4/5)*d/dx)^n when n=0,2,4,6,...

Terms

a(0) =1a(1) =1a(2) =5a(3) =6a(4) =60a(5) =25a(6) =66a(7) =990a(8) =825a(9) =125a(10) =1056a(11) =21120a(12) =26400a(13) =8000a(14) =625a(15) =22176a(16) =554400a(17) =924000a(18) =420000a(19) =65625a(20) =3125a(21) =576576a(22) =17297280a(23) =36036000a(24) =21840000a(25) =5118750a(26) =487500a(27) =15625a(28) =17873856a(29) =625584960