a(n+3) = 3*a(n+2) - 2*a(n+1) + 1 with a(0)=1, a(1)=5.

Terms

a(0) =1a(1) =5a(2) =14a(3) =33a(4) =72a(5) =151a(6) =310a(7) =629a(8) =1268a(9) =2547a(10) =5106a(11) =10225a(12) =20464a(13) =40943a(14) =81902a(15) =163821a(16) =327660a(17) =655339a(18) =1310698a(19) =2621417a(20) =5242856a(21) =10485735a(22) =20971494a(23) =41943013a(24) =83886052a(25) =167772131a(26) =335544290a(27) =671088609a(28) =1342177248a(29) =2684354527