OFFSET
1,1
COMMENTS
Neither p nor q can equal 2, i.e., 2 is not a permissible prime here. - Harvey P. Dale, May 04 2011
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
(3 - 1) divides (5 - 1), so 3 * 5 = 15 is in this sequence.
(5 - 1) divides (17 - 1) so 5 * 17 = 85 is in this sequence.
(5 - 1) does not divide (19 - 1), so 5 * 19 = 95 is not in this sequence.
MATHEMATICA
Table[If[i < j && IntegerQ[(Prime[j] - 1)/(Prime[i] - 1)], Prime[j] * Prime[i]], {i, 2, 100}, {j, 2, 100}] // Flatten // Union
Union[Times@@@Select[Subsets[Prime[Range[2, 100]], {2}], Divisible[Last[#] - 1, First[#] - 1] &]] (* Harvey P. Dale, May 04 2011 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
José María Grau Ribas, Dec 11 2010
STATUS
approved