a(n) = gcd(prime(n)+prime(n+1), prime(n+1)+prime(n+2)).

Terms

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