Number of length-n binary strings that neither begin nor end with a square.

Terms

a(0) =2a(1) =2a(2) =2a(3) =2a(4) =6a(5) =8a(6) =16a(7) =26a(8) =44a(9) =88a(10) =160a(11) =318a(12) =620a(13) =1234a(14) =2434a(15) =4860a(16) =9664a(17) =19282a(18) =38450a(19) =76804a(20) =153362a(21) =306524a(22) =612576a(23) =1224770a(24) =2448594a(25) =4896428a(26) =9790988a(27) =19580486a(28) =39157180a(29) =78311372