Power ceiling-floor sequence of 2 + sqrt(3).

Terms

a(0) =4a(1) =14a(2) =53a(3) =197a(4) =736a(5) =2746a(6) =10249a(7) =38249a(8) =142748a(9) =532742a(10) =1988221a(11) =7420141a(12) =27692344a(13) =103349234a(14) =385704593a(15) =1439469137a(16) =5372171956a(17) =20049218686a(18) =74824702789a(19) =279249592469