A065957 This is the case k = 3 of the number of orbits of the group of units of Z/(n) acting naturally on the k-subsets of Z/(n).

1, 3, 3, 12, 7, 20, 16, 32, 17, 72, 25, 64, 65, 89, 43, 148, 55, 172, 123, 156, 81, 334, 118, 220, 175, 322, 131, 556, 151, 374, 291, 376, 289, 735, 217, 472, 405, 766, 267, 1028, 295, 760, 659, 692, 353, 1368, 446, 1008, 685, 1054, 451, 1484, 681, 1398, 855

Offset: 3

Author

W. Edwin Clark, Jul 15 2001

Keywords

• nonn

Examples

			a(4) = 3 since when U(4) = {1,3} acts naturally on the three 3-subsets {0,1,2}, {0,1,3}, {0,2,3}, {1,2,3} of Z/(4) the orbits are {{0,1,2},{0,2,3}}, {{0,1,3}} and {{1,2,3}}. Note that 3{0,1,2} = {0,2,3}.
		

Crossrefs

Cf. A063379, A063381, A000005, A056376 + 1, A056371 - 1.

Extensions

More terms from Sean A. Irvine, Apr 22 2023