Numbers k such that k^2 divides k.k.k where dot "." means concatenation.

Terms

a(0) =1a(1) =3a(2) =13a(3) =21a(4) =37a(5) =39a(6) =91a(7) =1443a(8) =3367a(9) =9901a(10) =157737a(11) =333667a(12) =999001a(13) =3075403a(14) =9226209a(15) =14287143a(16) =33336667a(17) =99990001a(18) =1171182883a(19) =1224848037a(20) =1286294191a(21) =1397863441a(22) =1428557143a(23) =1469179621a(24) =1535254357a(25) =1568996211a(26) =1753536967a(27) =1792076241a(28) =1839599913a(29) =1891910811