a(n) = (p-5)(p-7)/24, where p=prime(n).

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =5a(5) =7a(6) =12a(7) =22a(8) =26a(9) =40a(10) =51a(11) =57a(12) =70a(13) =92a(14) =117a(15) =126a(16) =155a(17) =176a(18) =187a(19) =222a(20) =247a(21) =287a(22) =345a(23) =376a(24) =392a(25) =425a(26) =442a(27) =477a(28) =610a(29) =651