Number of binary sequences of length n containing exactly one subsequence 0101.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =4a(6) =10a(7) =24a(8) =57a(9) =128a(10) =278a(11) =596a(12) =1260a(13) =2628a(14) =5430a(15) =11136a(16) =22683a(17) =45936a(18) =92574a(19) =185764a(20) =371347a(21) =739840a(22) =1469580a(23) =2911224a(24) =5753048a(25) =11343800a(26) =22322444a(27) =43845120a(28) =85973013a(29) =168314604