a(n) is root of square starting with digit 3: first term of runs.

Terms

a(0) =6a(1) =18a(2) =55a(3) =174a(4) =548a(5) =1733a(6) =5478a(7) =17321a(8) =54773a(9) =173206a(10) =547723a(11) =1732051a(12) =5477226a(13) =17320509a(14) =54772256a(15) =173205081a(16) =547722558a(17) =1732050808a(18) =5477225576a(19) =17320508076a(20) =54772255751a(21) =173205080757a(22) =547722557506