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

1,1

Links

Table of n, a(n) for n=1..55.

Formula

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

Example

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.

Sequence in context: A378541 A378599 A370205 * A145278 A094371 A286927

Adjacent sequences: A304388 A304389 A304390 * A304392 A304393 A304394

Keyword

nonn,easy

Author

David A. Corneth, May 24 2018

Status

approved