Numbers k such that k*(k+3) gives the concatenation of two numbers m and m-2.

Terms

a(0) =9a(1) =99a(2) =362a(3) =636a(4) =713a(5) =922a(6) =999a(7) =8904a(8) =9999a(9) =81817a(10) =99999a(11) =336632a(12) =663366a(13) =999999a(14) =7272726a(15) =9999999a(16) =76470588a(17) =99999999a(18) =333666332a(19) =405436667a(20) =428571428a(21) =447710184a(22) =454545453a(23) =473684210a(24) =526315788a(25) =545454545a(26) =552289814