a(n) = 3*a(n-1) - a(n-2) with a(0)=1, a(1)=11.

Terms

a(0) =1a(1) =11a(2) =32a(3) =85a(4) =223a(5) =584a(6) =1529a(7) =4003a(8) =10480a(9) =27437a(10) =71831a(11) =188056a(12) =492337a(13) =1288955a(14) =3374528a(15) =8834629a(16) =23129359a(17) =60553448a(18) =158530985a(19) =415039507a(20) =1086587536a(21) =2844723101a(22) =7447581767a(23) =19498022200a(24) =51046484833a(25) =133641432299