a(1)=1; for n > 1, a(n) = 7*a(n-1) + n.

Terms

a(0) =1a(1) =9a(2) =66a(3) =466a(4) =3267a(5) =22875a(6) =160132a(7) =1120932a(8) =7846533a(9) =54925741a(10) =384480198a(11) =2691361398a(12) =18839529799a(13) =131876708607a(14) =923136960264