Number of compositions of n with exactly 1 adjacent equal pair of parts.

Terms

a(0) =1a(1) =0a(2) =3a(3) =6a(4) =7a(5) =20a(6) =42a(7) =72a(8) =141a(9) =280a(10) =516a(11) =976a(12) =1853a(13) =3420a(14) =6361a(15) =11844a(16) =21819a(17) =40192a(18) =73942a(19) =135452a(20) =247828a(21) =452776a(22) =825252a(23) =1501998a(24) =2730159a(25) =4954890a(26) =8981360a(27) =16261568a(28) =29408708a(29) =53130154