Number of binary words of length n with an even number of occurrences of the subword 0101.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =15a(5) =28a(6) =54a(7) =104a(8) =198a(9) =380a(10) =736a(11) =1424a(12) =2756a(13) =5360a(14) =10456a(15) =20416a(16) =39944a(17) =78352a(18) =153952a(19) =302912a(20) =596976a(21) =1178304a(22) =2328544a(23) =4606848a(24) =9124448a(25) =18089920a(26) =35895552a(27) =71283968a(28) =141664832a(29) =281718528