A268578 Numbers n such that n+2, n+4, n+6, n+8, n+10, n+12 and n+14 are all semiprimes.
3089, 8127, 8129, 9981, 9983, 55557, 92601, 99441, 99443, 112707, 132075, 132077, 182747, 190935, 190937, 209477, 237447, 237449, 239087, 249687, 296777, 300447, 313409, 401427, 401429, 441675, 441677, 452637, 452639, 547155, 604485, 604487, 631199, 650999
Offset: 1
Keywords
Examples
8127 is in sequence because 8127+2 = 11*739, 8127+4 = 47*173, 8127+6 = 3*2711, 8127+8 = 5*1627, 8127+10 = 79*103, 8127+12 = 3*2713, 8127+14 = 7*1163 are all semiprime.
Links
- Chai Wah Wu, Table of n, a(n) for n = 1..6115
Crossrefs
Cf. A268862 (primes of the sequence).
Programs
-
Magma
IsSemiprime := func
; [n: n in [2..700000] | forall{i: i in [2..14 by 2] | IsSemiprime(n+i)}]; -
Mathematica
Select[Range[400000], Union[PrimeOmega[# + {2, 4, 6, 8, 10, 12, 14}]] == {2} &]
Comments