a(n) is root of square starting with digit 2: first term of runs.

Terms

a(0) =5a(1) =15a(2) =45a(3) =142a(4) =448a(5) =1415a(6) =4473a(7) =14143a(8) =44722a(9) =141422a(10) =447214a(11) =1414214a(12) =4472136a(13) =14142136a(14) =44721360a(15) =141421357a(16) =447213596a(17) =1414213563a(18) =4472135955a(19) =14142135624a(20) =44721359550a(21) =141421356238a(22) =447213595500