a(0)=a(1)=1, a(2)=6, a(3)=11; a(n+4) = 10*a(n+2) - a(n).

Terms

a(0) =1a(1) =1a(2) =6a(3) =11a(4) =59a(5) =109a(6) =584a(7) =1079a(8) =5781a(9) =10681a(10) =57226a(11) =105731a(12) =566479a(13) =1046629a(14) =5607564a(15) =10360559a(16) =55509161a(17) =102558961a(18) =549484046a(19) =1015229051a(20) =5439331299a(21) =10049731549a(22) =53843828944a(23) =99482086439a(24) =532998958141a(25) =984771132841