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A318591 Number of n-member subsets of [3*n] whose elements sum to a multiple of three. 2
1, 1, 5, 30, 165, 1001, 6198, 38760, 245157, 1562331, 10015005, 64512240, 417226230, 2707475148, 17620076360, 114955810530, 751616304549, 4923689695575, 32308782871911, 212327989773900, 1397281501935165, 9206478467531865, 60727722660586800, 400978991944396320 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000

EXAMPLE

a(2) = 5: {1,2}, {1,5}, {2,4}, {3,6}, {4,5}.

CROSSREFS

Column k=3 of A318557.

Sequence in context: A254944 A003731 A055838 * A094972 A084158 A111469

Adjacent sequences:  A318588 A318589 A318590 * A318592 A318593 A318594

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Aug 29 2018

STATUS

approved

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Last modified April 18 08:37 EDT 2019. Contains 322209 sequences. (Running on oeis4.)