A015632 Number of ordered triples of integers from [ 1,n ] with no common factors between pairs.

1, 2, 4, 6, 12, 14, 26, 33, 46, 52, 84, 91, 137, 152, 174, 199, 279, 295, 397, 425, 475, 513, 663, 692, 819, 876, 986, 1044, 1286, 1315, 1593, 1700, 1838, 1939, 2123, 2186, 2582, 2711, 2905, 3008, 3498, 3564, 4106, 4272, 4476, 4666, 5316, 5433, 5985

Offset

1,2

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..500

Formula

a(n) ~ k * n^3 where k is 1/6 * A065473 = 0.04779.... [Charles R Greathouse IV, Nov 14 2011]

Prog

(Haskell)
a015632 n = length [(x, y, z) | z <- [1..n], y <- [1..z], gcd y z == 1,
                              x <- [1..y], gcd x z == 1, gcd x y == 1]
-- Reinhard Zumkeller, Nov 14 2011

Crossrefs

Sequence in context: A161337 A050055 A293602 * A111084 A015636 A015663

Adjacent sequences: A015629 A015630 A015631 * A015633 A015634 A015635

Keyword

nonn

Author

Olivier Gérard

Status

approved