a(n) = 680*2^n - 622.

Terms

a(0) =58a(1) =738a(2) =2098a(3) =4818a(4) =10258a(5) =21138a(6) =42898a(7) =86418a(8) =173458a(9) =347538a(10) =695698a(11) =1392018a(12) =2784658a(13) =5569938a(14) =11140498a(15) =22281618a(16) =44563858a(17) =89128338a(18) =178257298a(19) =356515218a(20) =713031058a(21) =1426062738a(22) =2852126098a(23) =5704252818a(24) =11408506258a(25) =22817013138a(26) =45634026898a(27) =91268054418a(28) =182536109458a(29) =365072219538