cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A092128 Numbers n such that n, n+2, n+4, n+6, n+8, n+10 are semiprimes.

Original entry on oeis.org

1383, 3091, 3093, 5609, 8129, 8131, 8133, 9753, 9983, 9985, 9987, 10401, 11013, 12053, 13637, 16499, 22457, 30991, 43339, 45803, 49083, 53761, 55559, 55561, 58277, 63047, 63951, 64829, 69603, 71727, 76803, 80633, 92603, 92605, 98493
Offset: 1

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Author

Zak Seidov, Feb 22 2004

Keywords

Comments

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

Crossrefs

Programs

  • Mathematica
    PrimeFactorExponentsAdded[n_] := Plus @@ Flatten[Table[ #[[2]], {1}] & /@ FactorInteger[n]]; Select[ Range[ 99210], PrimeFactorExponentsAdded[ # ] == PrimeFactorExponentsAdded[ # + 2] == PrimeFactorExponentsAdded[ # + 4] == PrimeFactorExponentsAdded[ # + 6] == PrimeFactorExponentsAdded[ # + 8] == PrimeFactorExponentsAdded[ # + 10] == 2 &] (* Robert G. Wilson v, Feb 24 2004 *)
    spQ[n_]:=PrimeOmega[n]==2; Select[Range[100000],AllTrue[#+{0,2,4,6,8,10},spQ]&] (* Harvey P. Dale, Dec 19 2021 *)

Extensions

More terms from Don Reble, Feb 23 2004
More terms from Robert G. Wilson v, Feb 24 2004