a(n) = 11*7^n + 1.

Terms

a(0) =12a(1) =78a(2) =540a(3) =3774a(4) =26412a(5) =184878a(6) =1294140a(7) =9058974a(8) =63412812a(9) =443889678a(10) =3107227740a(11) =21750594174a(12) =152254159212