A216302 Numbers k such that 10k+9 is composite but 10k+1, 10k+3, 10k+7 are all prime.

4, 31, 46, 64, 88, 109, 130, 367, 400, 493, 523, 550, 823, 829, 886, 946, 1033, 1117, 1369, 1390, 1408, 1432, 1825, 1999, 2161, 2329, 2356, 2374, 2503, 2626, 2668, 2671, 2794, 2902, 3049, 3139, 3151, 3154, 3232, 3253, 3421, 3553, 3559, 3601, 3799, 3904

Offset

1,1

Links

V. Raman, Table of n, a(n) for n = 1..10000

Formula

a(n) >> n log^3 n. - Charles R Greathouse IV, Sep 07 2012

Mathematica

t = {}; Do[ps = Select[Range[10*n, 10*n + 9], PrimeQ]; If[ps == {10*n + 1, 10*n + 3, 10*n + 7}, AppendTo[t, n]], {n, 0, 4903}]; t (* T. D. Noe, Sep 03 2012 *)
Select[Range[4000], !PrimeQ[10#+9]&&And@@PrimeQ[10#+{1, 3, 7}]&] (* Harvey P. Dale, May 23 2014 *)

Crossrefs

Cf. A032352, A007811, A078494.

Sequence in context: A025416 A043082 A371034 * A070522 A087689 A330788

Adjacent sequences: A216299 A216300 A216301 * A216303 A216304 A216305

Keyword

nonn

Author

V. Raman, Sep 03 2012

Status

approved