A145312(n)/1440.

Terms

a(0) =3a(1) =28a(2) =146a(3) =420a(4) =1260a(5) =2408a(6) =5460a(7) =9084a(8) =17010a(9) =24420a(10) =44968a(11) =57148a(12) =93912a(13) =123480a(14) =187240a(15) =222768a(16) =347463a(17) =391020a(18) =582540a(19) =674240a(20) =923076a(21) =1026168a(22) =1506960a(23) =1575100a(24) =2143050a(25) =2391480a(26) =3164112a(27) =3300780a(28) =4604040a(29) =4617760