a(n) = (n+1)*a(n-5), with a(0)=a(1)=a(2)=a(3)=a(4)=1.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =6a(6) =7a(7) =8a(8) =9a(9) =10a(10) =66a(11) =84a(12) =104a(13) =126a(14) =150a(15) =1056a(16) =1428a(17) =1872a(18) =2394a(19) =3000a(20) =22176a(21) =31416a(22) =43056a(23) =57456a(24) =75000a(25) =576576a(26) =848232a(27) =1205568a(28) =1666224a(29) =2250000