Number of binary vectors of length n+1 beginning with 0 and containing just 1 singleton.

Terms

a(0) =1a(1) =0a(2) =2a(3) =2a(4) =5a(5) =8a(6) =15a(7) =26a(8) =46a(9) =80a(10) =139a(11) =240a(12) =413a(13) =708a(14) =1210a(15) =2062a(16) =3505a(17) =5944a(18) =10059a(19) =16990a(20) =28646a(21) =48220a(22) =81047a(23) =136032a(24) =228025a(25) =381768a(26) =638450a(27) =1066586a(28) =1780061a(29) =2968040