a(n) = [ a(n-1)/(sqrt(6) - 2) ], where a(0) = 1.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =17a(5) =37a(6) =82a(7) =182a(8) =404a(9) =898a(10) =1997a(11) =4442a(12) =9882a(13) =21984a(14) =48908a(15) =108807a(16) =242067a(17) =538537a(18) =1198107a(19) =2665482a(20) =5930017a(21) =13192774a(22) =29350556a(23) =65297498a(24) =145270273a(25) =323189294a(26) =719013724a(27) =1599622094a(28) =3558751049a(29) =7917313144