2*a(n) is the least number where k sets a new record such that 2*a(n)-k and 2*a(n)+k are prime and at least one of 2*a(n)-j and 2*a(n)+j is composite for all 0<j<k.
A307881
2*a(n) is the least number where k sets a new record such that 2*a(n)-k and 2*a(n)+k are prime and at least one of 2*a(n)-j and 2*a(n)+j is composite for all 0<j<k.
Terms
- a(0) =2a(1) =4a(2) =11a(3) =23a(4) =64a(5) =68a(6) =73a(7) =119a(8) =143a(9) =172a(10) =263a(11) =452a(12) =557a(13) =868a(14) =1238a(15) =1579a(16) =2864a(17) =3533a(18) =3637a(19) =4252a(20) =5171a(21) =9263a(22) =11282a(23) =12388a(24) =20036a(25) =59119a(26) =69332a(27) =90131a(28) =113783a(29) =139283
External references
- oeis: A307881