a(n) = 2*a(n-1) + a(n-2) + n.

Terms

a(0) =1a(1) =3a(2) =9a(3) =24a(4) =61a(5) =151a(6) =369a(7) =896a(8) =2169a(9) =5243a(10) =12665a(11) =30584a(12) =73845a(13) =178287a(14) =430433a(15) =1039168a(16) =2508785a(17) =6056755a(18) =14622313a(19) =35301400a(20) =85225133a(21) =205751687a(22) =496728529a(23) =1199208768a(24) =2895146089a(25) =6989500971a(26) =16874148057a(27) =40737797112a(28) =98349742309