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A092126
Numbers n such that n, n+2, n+4, n+6 are semiprimes.
10
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
1,1
COMMENTS
Semiprimes in arithmetic progression. All terms are odd, see also A056809.
LINKS
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 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Zak Seidov, Feb 22 2004
STATUS
approved