Smallest even k such that the pair {k-3,k-1} is not a twin prime pair and lpf(k-1) > lpf(k-3) >= prime(n), where lpf = least prime factor (A020639).
A242720
Smallest even k such that the pair {k-3,k-1} is not a twin prime pair and lpf(k-1) > lpf(k-3) >= prime(n), where lpf = least prime factor (A020639).
Terms
- a(0) =12a(1) =38a(2) =80a(3) =212a(4) =224a(5) =440a(6) =440a(7) =854a(8) =1250a(9) =1460a(10) =1742a(11) =2282a(12) =2282a(13) =3434a(14) =4190a(15) =4664a(16) =4760a(17) =4760a(18) =6890a(19) =8054a(20) =8054a(21) =8054a(22) =12374a(23) =12830a(24) =12830a(25) =13592a(26) =13592a(27) =14282a(28) =17402a(29) =17402
External references
- oeis: A242720