A001897 with terms repeated.

Terms

a(0) =1a(1) =1a(2) =3a(3) =3a(4) =15a(5) =15a(6) =21a(7) =21a(8) =15a(9) =15a(10) =33a(11) =33a(12) =1365a(13) =1365a(14) =3a(15) =3a(16) =255a(17) =255a(18) =399a(19) =399a(20) =165a(21) =165a(22) =69a(23) =69a(24) =1365a(25) =1365a(26) =3a(27) =3a(28) =435a(29) =435