a(n+5) = a(n+4)+a(n+3)+a(n+2)+a(n+1)+2*a(n) with a(0)=2, a(1)=1, a(2)=5, a(3)=10, a(4)=20.

Terms

a(0) =2a(1) =1a(2) =5a(3) =10a(4) =20a(5) =40a(6) =77a(7) =157a(8) =314a(9) =628a(10) =1256a(11) =2509a(12) =5021a(13) =10042a(14) =20084a(15) =40168a(16) =80333a(17) =160669a(18) =321338a(19) =642676a(20) =1285352a(21) =2570701a(22) =5141405a(23) =10282810a(24) =20565620a(25) =41131240a(26) =82262477a(27) =164524957a(28) =329049914a(29) =658099828