Number of compositions of 7*n into parts 1 and 7.

Terms

a(0) =1a(1) =2a(2) =10a(3) =53a(4) =264a(5) =1294a(6) =6349a(7) =31200a(8) =153366a(9) =753836a(10) =3705166a(11) =18211117a(12) =89508951a(13) =439943336a(14) =2162355196a(15) =10628140702a(16) =52238121106a(17) =256754344524