a(0)=1, a(1)=5, a(n) = -3*a(n-1), n>1.

Terms

a(0) =1a(1) =5a(2) =-15a(3) =45a(4) =-135a(5) =405a(6) =-1215a(7) =3645a(8) =-10935a(9) =32805a(10) =-98415a(11) =295245a(12) =-885735a(13) =2657205a(14) =-7971615a(15) =23914845a(16) =-71744535a(17) =215233605a(18) =-645700815a(19) =1937102445a(20) =-5811307335a(21) =17433922005a(22) =-52301766015a(23) =156905298045a(24) =-470715894135