a(n) = prime(n+4) - prime(n).

Terms

a(0) =9a(1) =10a(2) =12a(3) =12a(4) =12a(5) =16a(6) =14a(7) =18a(8) =18a(9) =14a(10) =16a(11) =16a(12) =18a(13) =18a(14) =20a(15) =18a(16) =14a(17) =18a(18) =16a(19) =18a(20) =24a(21) =22a(22) =20a(23) =18a(24) =12a(25) =12a(26) =24a(27) =24a(28) =28a(29) =26