a(1)=1, a(n) = 5*a(n-1) + n.

Terms

a(0) =1a(1) =7a(2) =38a(3) =194a(4) =975a(5) =4881a(6) =24412a(7) =122068a(8) =610349a(9) =3051755a(10) =15258786a(11) =76293942a(12) =381469723a(13) =1907348629a(14) =9536743160a(15) =47683715816a(16) =238418579097