OFFSET
1,1
COMMENTS
The computations were done without any assumptions on the form of d.
LINKS
Sameen Ahmed Khan, Table of n, a(n) for n = 1..10000
Sameen Ahmed Khan, Primes in Geometric-Arithmetic Progression, arXiv preprint arXiv:1203.2083 [math.NT], 2012. - From N. J. A. Sloane, Sep 15 2012
EXAMPLE
d = 150 then {7, 7 + 1*150, 7 + 2*150, 7 + 3*150, 7 + 4*150, 7 + 5*150} = {7, 157, 307, 457, 607, 757} which is 6 primes in arithmetic progression.
MATHEMATICA
a = 7; t = {}; Do[If[PrimeQ[{a, a + d, a + 2*d, a + 3*d, a + 4*d, a + 5*d}] == {True, True, True, True, True, True}, AppendTo[t, d]], {d, 300000}]; t
Select[Range[250000], AllTrue[7+#*Range[0, 5], PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Dec 26 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Sameen Ahmed Khan, Feb 03 2012
STATUS
approved