A115447 Numbers whose square is the concatenation of two numbers k and k-9.
71, 7235, 9701, 798981, 997001, 35324118, 64675883, 99970001, 3297392379, 6702607622, 7890726434, 8812181189, 9999700001, 897807218979, 917811219179, 979998999801, 999997000001, 46193210013657, 49751928874867
Offset: 1
Examples
638370_638361 = 798981^2.