A304391 Numbers that are the number of permutations of a set of balls of at least three distinct colors.

6, 12, 20, 24, 30, 42, 56, 60, 72, 90, 105, 110, 120, 132, 140, 156, 168, 180, 182, 210, 240, 252, 272, 280, 306, 336, 342, 360, 380, 420, 462, 495, 504, 506, 552, 560, 600, 630, 650, 660, 702, 720, 756, 812, 840, 858, 870, 930, 990, 992, 1056, 1092, 1120, 1122, 1190

Offset: 1

Author

David A. Corneth, May 24 2018

Keywords

• nonn
• easy

Examples

			There are 30 permutations of 5 balls where 2 are red, 2 are yellow and 1 is blue.
		

Crossrefs

A002378 is a subsequence.

Cf. A027480, A304938.

Formula

A027480(k) = k * (k + 1) * (k + 2) / 2 is in the sequence for k >= 2.