A216308 Values of k such that 10*k+7 and 10*k+9 are the only primes between 10*k and 10*k+9.

34, 127, 202, 223, 226, 265, 352, 355, 412, 433, 454, 463, 496, 619, 694, 730, 838, 853, 859, 967, 976, 1000, 1003, 1042, 1093, 1105, 1171, 1177, 1321, 1339, 1399, 1438, 1444, 1486, 1528, 1741, 1759, 1765, 1774, 1783, 1795, 1828, 1969, 2047, 2050, 2071, 2080

Offset: 1

Author

V. Raman, Sep 03 2012

Keywords

• nonn

Links

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

Crossrefs

Cf. A032352, A007811, A078494.

Programs

Mathematica

t = {}; Do[ps = Select[Range[10*n, 10*n + 9], PrimeQ]; If[ps == {10*n + 7, 10*n + 9}, AppendTo[t, n]], {n, 0, 2599}]; t (* T. D. Noe, Sep 04 2012 *)

Formula

a(n) >> n log^2 n. - Charles R Greathouse IV, Sep 07 2012