a(n) = prime(prime(prime(n))) - prime(prime(n)).

Terms

a(0) =2a(1) =6a(2) =20a(3) =42a(4) =96a(5) =138a(6) =218a(7) =264a(8) =348a(9) =490a(10) =582a(11) =762a(12) =884a(13) =962a(14) =1086a(15) =1282a(16) =1510a(17) =1564a(18) =1890a(19) =2028a(20) =2110a(21) =2348a(22) =2570a(23) =2798a(24) =3128a(25) =3396a(26) =3528a(27) =3686a(28) =3798a(29) =3932