a(n) = 4*(23 - 17*n + 8*n^2).

Terms

a(0) =56a(1) =84a(2) =176a(3) =332a(4) =552a(5) =836a(6) =1184a(7) =1596a(8) =2072a(9) =2612a(10) =3216a(11) =3884a(12) =4616a(13) =5412a(14) =6272a(15) =7196a(16) =8184a(17) =9236a(18) =10352a(19) =11532a(20) =12776a(21) =14084a(22) =15456a(23) =16892a(24) =18392a(25) =19956a(26) =21584a(27) =23276a(28) =25032a(29) =26852