A392186 Semiprimes k such that k+2 and k+6 are primes and k+4 and k+8 are all semiprimes.

485, 497, 2855, 3035, 5165, 5345, 6005, 6995, 7037, 15437, 15677, 19007, 22805, 23597, 24437, 25937, 37487, 40187, 41645, 44837, 46745, 57635, 58655, 65177, 83087, 89777, 93977, 96905, 102545, 104237, 105965, 120845, 123995, 128387, 141437, 142055, 157997

Offset

1,1

Comments

For all k in the sequence, k+2 and k+6 are primes and k, k+4 and k+8 are semiprimes.

Links

Michael De Vlieger, Table of n, a(n) for n = 1..10000

Example

19007 = 83*229; 19009 is prime; 19011 = 3*6337; 19013 is prime; 19015 = 5*3803.

Maple

q:= k-> andmap(isprime, [k+2, k+6]) and andmap(numtheory[bigomega]=2, [k, k+4, k+8]):
select(q, [6*i+5$i=0..26332])[];  # Alois P. Heinz, Jan 07 2026

Mathematica

okQ[k_]:=PrimeOmega[k]==2&&PrimeQ[k+2]&&PrimeQ[k+6]&&PrimeOmega[k+4]==2&&PrimeOmega[k+8]==2; Select[Range[160000], okQ] (* James C. McMahon, Jan 20 2026 *)

Crossrefs

Subsequence of A016969.

Cf. A000040, A001358, A175710.

Sequence in context: A013771 A114774 A013903 * A160090 A158326 A031722

Adjacent sequences: A392183 A392184 A392185 * A392187 A392188 A392189

Keyword

nonn

Author

Soko Kosaka, Jan 02 2026

Status

approved