Squares of terms are the intersection of A025487 and A217584.

Terms

a(0) =1a(1) =12a(2) =60a(3) =1260a(4) =13860a(5) =180180a(6) =277200a(7) =900900a(8) =3628800a(9) =15315300a(10) =28828800a(11) =38880000a(12) =290990700a(13) =373248000a(14) =428828400a(15) =2036934900a(16) =2477260800a(17) =3632428800a(18) =6692786100a(19) =8147739600a(20) =13335840000a(21) =15682867200a(22) =15925248000a(23) =20956320000a(24) =46849502700a(25) =61751289600a(26) =65181916800a(27) =68976230400