Number of binary strings of length n such that there exist three consecutive digits where at least two of them are 1's.

A118645

Number of binary strings of length n such that there exist three consecutive digits where at least two of them are 1's.

Terms

    a(0) =0a(1) =0a(2) =1a(3) =4a(4) =10a(5) =23a(6) =51a(7) =109a(8) =228a(9) =471a(10) =964a(11) =1960a(12) =3967a(13) =8003a(14) =16107a(15) =32362a(16) =64941a(17) =130200a(18) =260866a(19) =522415a(20) =1045831a(21) =2093129a(22) =4188408a(23) =8379967a(24) =16764552a(25) =33535872a(26) =67081663a(27) =134177863a(28) =268377031a(29) =536785286

External references