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

Terms

a(0) =1a(1) =5a(2) =10a(3) =35a(4) =85a(5) =260a(6) =685a(7) =1985a(8) =5410a(9) =15335a(10) =42385a(11) =119060a(12) =330985a(13) =926285a(14) =2581210a(15) =7212635a(16) =20118685a(17) =56181860a(18) =156775285a(19) =437684585a(20) =1221561010a(21) =3409983935a(22) =9517788985a(23) =26567708660a(24) =74156653585a(25) =206995196885a(26) =577778464810