a(n) = 2*((-1)^n - 1)*(F(n) - 1) - (3*(-1)^n + 7)/2 * F(n+1) + 5*F(n+1)^2.

Terms

a(0) =0a(1) =3a(2) =10a(3) =35a(4) =100a(5) =288a(6) =780a(7) =2115a(8) =5610a(9) =14883a(10) =39160a(11) =103040a(12) =270280a(13) =708963a(14) =1857450a(15) =4866435a(16) =12744060a(17) =33373728a(18) =87382900a(19) =228795875a(20) =599019850a(21) =1568318403a(22) =4105974960a(23) =10749749760a(24) =28143378000a(25) =73680759363a(26) =192899171530a(27) =505017737315