Number of binary sequences of length n containing exactly one subsequence 0011.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =4a(6) =12a(7) =32a(8) =78a(9) =180a(10) =400a(11) =864a(12) =1827a(13) =3800a(14) =7800a(15) =15840a(16) =31884a(17) =63704a(18) =126480a(19) =249760a(20) =490885a(21) =960828a(22) =1873828a(23) =3642560a(24) =7060314a(25) =13649196a(26) =26324704a(27) =50662464a(28) =97309767a(29) =186571248