A115555 Numbers k such that the concatenation of 9*k with k gives a square.
1836734693877551020408163265306122449, 7346938775510204081632653061224489796, 15311909262759924385633270321361058601134215500945179584121, 27221172022684310018903591682419659735349716446124763705104
Offset: 1