a(n) = prime(n)^2-4.

Terms

a(0) =0a(1) =5a(2) =21a(3) =45a(4) =117a(5) =165a(6) =285a(7) =357a(8) =525a(9) =837a(10) =957a(11) =1365a(12) =1677a(13) =1845a(14) =2205a(15) =2805a(16) =3477a(17) =3717a(18) =4485a(19) =5037a(20) =5325a(21) =6237a(22) =6885a(23) =7917a(24) =9405a(25) =10197a(26) =10605a(27) =11445a(28) =11877a(29) =12765