Numbers k such that k * (k+6) is the concatenation of a number m with itself.

Terms

a(0) =5a(1) =95a(2) =462a(3) =533a(4) =715a(5) =819a(6) =995a(7) =3425a(8) =6570a(9) =9995a(10) =90904a(11) =99995a(12) =980199a(13) =999995a(14) =3636358a(15) =6363637a(16) =9999995a(17) =41176465a(18) =58823530a(19) =99999995a(20) =413533835a(21) =426573427a(22) =428571423a(23) =432620006a(24) =567379989a(25) =571428572a(26) =573426568a(27) =586466160a(28) =686261108a(29) =725274726