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A304391
Numbers that are the number of permutations of a set of balls of at least three distinct colors.
0
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
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.
Sequence in context: A246198 A083207 A370205 * A145278 A094371 A286927
KEYWORD
nonn,easy
AUTHOR
David A. Corneth, May 24 2018
STATUS
approved