A092126 Numbers n such that n, n+2, n+4, n+6 are semiprimes.

213, 215, 299, 411, 1133, 1135, 1343, 1345, 1383, 1385, 1387, 1685, 1793, 1835, 1837, 1891, 1937, 1939, 1957, 2045, 2315, 2317, 2513, 2567, 2807, 2809, 2929, 3091, 3093, 3095, 3097, 3147, 3149, 3647, 3957, 3977, 3979, 4115, 4313, 4315, 4411, 4529, 4531

Offset: 1

Author

Zak Seidov, Feb 22 2004

Keywords

• easy
• nonn

Comments

Semiprimes in arithmetic progression. All terms are odd, see also A056809.

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A056809, A070552, A092125, A092127, A092128, A092129.

Programs

Mathematica

PrimeFactorExponentsAdded[n_] := Plus @@ Flatten[Table[ #[[2]], {1}] & /@ FactorInteger[n]]; Select[ Range[ 4626], PrimeFactorExponentsAdded[ # ] == PrimeFactorExponentsAdded[ # + 2] == PrimeFactorExponentsAdded[ # + 4] == PrimeFactorExponentsAdded[ # + 6] == 2 &] (* Robert G. Wilson v, Feb 24 2004 *)
Transpose[SequencePosition[Table[If[PrimeOmega[n]==2,1,0],{n,5000}],{1,,1,,1,,1}]][[1]] (* The program uses the SequencePosition function from Mathematica version 10 *) (* _Harvey P. Dale, Feb 10 2016 *)