Number of compositions of 7*n into parts 4 and 7.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =9a(6) =37a(7) =121a(8) =332a(9) =808a(10) =1837a(11) =4113a(12) =9497a(13) =23091a(14) =58462a(15) =150129a(16) =382810a(17) =960520a(18) =2373982a(19) =5816480a(20) =14230964a(21) =34948927a(22) =86295036a(23) =213973997a(24) =531470618a(25) =1319411997a(26) =3270186871a(27) =8091796123a(28) =20002405065a(29) =49435009494