Number of compositions of n with exactly 2 transitions between different parts.

Terms

a(0) =1a(1) =4a(2) =14a(3) =29a(4) =56a(5) =100a(6) =148a(7) =230a(8) =322a(9) =446a(10) =573a(11) =778a(12) =953a(13) =1215a(14) =1456a(15) =1806a(16) =2134a(17) =2542a(18) =2944a(19) =3477a(20) =3968a(21) =4600a(22) =5186a(23) =5872a(24) =6657a(25) =7446a(26) =8304a(27) =9217a(28) =10258a(29) =11172