a(n)^3 is smallest cube containing exactly n 4's.

Terms

a(0) =4a(1) =14a(2) =114a(3) =164a(4) =763a(5) =3543a(6) =17066a(7) =13464a(8) =163974a(9) =757364a(10) =3421244a(11) =6727219a(12) =28902604a(13) =35685649a(14) =761777604a(15) =1350780517a(16) =2543012249a(17) =7633715304a(18) =101476238101a(19) =163186746514a(20) =353823251814