a(n+3) = 2*a(n+2) + a(n+1) + a(n) with a(0)=3, a(1)=2, a(2)=6.

Terms

a(0) =3a(1) =2a(2) =6a(3) =17a(4) =42a(5) =107a(6) =273a(7) =695a(8) =1770a(9) =4508a(10) =11481a(11) =29240a(12) =74469a(13) =189659a(14) =483027a(15) =1230182a(16) =3133050a(17) =7979309a(18) =20321850a(19) =51756059a(20) =131813277a(21) =335704463a(22) =854978262a(23) =2177474264a(24) =5545631253a(25) =14123715032a(26) =35970535581a(27) =91610417447a(28) =233315085507a(29) =594211124042