The 3rd Witt transform of A000217.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =3a(5) =15a(6) =54a(7) =165a(8) =429a(9) =999a(10) =2145a(11) =4290a(12) =8100a(13) =14586a(14) =25194a(15) =41985a(16) =67830a(17) =106590a(18) =163431a(19) =245157a(20) =360525a(21) =520749a(22) =740025a(23) =1036035a(24) =1430703a(25) =1950975a(26) =2629575a(27) =3506085a(28) =4628052a(29) =6052068