a(n) = (35*2^((2*(3*n+2) + 2)/3) - 2*(3*n+2) - 46)/9.

Terms

a(0) =10a(1) =56a(2) =242a(3) =988a(4) =3974a(5) =15920a(6) =63706a(7) =254852a(8) =1019438a(9) =4077784a(10) =16311170a(11) =65244716a(12) =260978902a(13) =1043915648a(14) =4175662634a(15) =16702650580a(16) =66810602366a(17) =267242409512