Number of binary sequences of length n with an even number of ones, at least two of the ones being contiguous.

A027711

Number of binary sequences of length n with an even number of ones, at least two of the ones being contiguous.

Terms

    a(0) =0a(1) =1a(2) =2a(3) =4a(4) =9a(5) =21a(6) =47a(7) =101a(8) =212a(9) =440a(10) =907a(11) =1859a(12) =3791a(13) =7699a(14) =15586a(15) =31476a(16) =63445a(17) =127689a(18) =256671a(19) =515433a(20) =1034248a(21) =2073968a(22) =4156791a(23) =8327911a(24) =16679007a(25) =33395527a(26) =66851750a(27) =133801708a(28) =267762321a(29) =535781757

External references