A216305 Values of k such that 10*k+1 and 10*k+9 alone are prime between 10*k and 10*k+9.

40, 49, 70, 76, 91, 157, 253, 274, 301, 304, 322, 349, 370, 388, 475, 505, 517, 622, 652, 715, 769, 817, 868, 931, 994, 1015, 1039, 1063, 1078, 1132, 1168, 1228, 1240, 1279, 1315, 1324, 1378, 1441, 1477, 1555, 1567, 1687, 1723, 1735, 1819, 1837, 1867, 1900

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 + 1, 10*n + 9}, AppendTo[t, n]], {n, 0, 3319}]; t (* T. D. Noe, Sep 04 2012 *)

Formula

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