a(n) is root of square starting with digit 7: first term of runs.

Terms

a(0) =27a(1) =84a(2) =265a(3) =837a(4) =2646a(5) =8367a(6) =26458a(7) =83667a(8) =264576a(9) =836661a(10) =2645752a(11) =8366601a(12) =26457514a(13) =83666003a(14) =264575132a(15) =836660027a(16) =2645751312a(17) =8366600266a(18) =26457513111a(19) =83666002654a(20) =264575131107a(21) =836660026535