a(n) = 12*n + 7^n - 5^n.

Terms

a(0) =0a(1) =14a(2) =48a(3) =254a(4) =1824a(5) =13742a(6) =102096a(7) =745502a(8) =5374272a(9) =38400590a(10) =272709744a(11) =1928498750a(12) =13597146720a(13) =95668307438a(14) =672119557392