a(1)=1; for n>1, a(n) = 8*a(n-1) + n.

Terms

a(0) =1a(1) =10a(2) =83a(3) =668a(4) =5349a(5) =42798a(6) =342391a(7) =2739136a(8) =21913097a(9) =175304786a(10) =1402438299a(11) =11219506404a(12) =89756051245a(13) =718048409974