In binary representation: least number, k, which occurs n times in its factorial.

Terms

a(0) =5a(1) =1a(2) =16a(3) =12a(4) =49a(5) =58a(6) =60a(7) =110a(8) =209a(9) =117a(10) =240a(11) =430a(12) =255a(13) =1423a(14) =921a(15) =980a(16) =511a(17) =1847a(18) =3737a(19) =3692a(20) =3998a(21) =7265a(22) =15267a(23) =15651a(24) =15722a(25) =31457a(26) =32659a(27) =64248a(28) =57927a(29) =64448