a(n) is the least number k such that A373531(k) = n, or -1 if no such k exists.

Terms

a(0) =1a(1) =2a(2) =12a(3) =120a(4) =240a(5) =3276a(6) =2520a(7) =10920a(8) =21840a(9) =32760a(10) =65520a(11) =622440a(12) =600600a(13) =900900a(14) =3636360a(15) =1801800a(16) =3603600a(17) =4455360a(18) =22407840a(19) =8910720a(20) =17821440a(21) =51351300a(22) =46060560a(23) =69090840a(24) =92121120a(25) =126977760a(26) =138181680a(27) =380933280a(28) =245044800a(29) =414545040