Number of compositions of n when each even part can be of two kinds.

Terms

a(0) =1a(1) =1a(2) =3a(3) =6a(4) =15a(5) =33a(6) =78a(7) =177a(8) =411a(9) =942a(10) =2175a(11) =5001a(12) =11526a(13) =26529a(14) =61107a(15) =140694a(16) =324015a(17) =746097a(18) =1718142a(19) =3956433a(20) =9110859a(21) =20980158a(22) =48312735a(23) =111253209a(24) =256191414a(25) =589951041a(26) =1358525283a(27) =3128378406a(28) =7203954255a(29) =16589089473