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A308667 (1/n) times the number of n-member subsets of [n^2] whose elements sum to a multiple of n. 3
1, 1, 10, 115, 2126, 54086, 1753074, 69159399, 3220837534, 173103073384, 10551652603526, 719578430425845, 54297978110913252, 4492502634538340722, 404469190271900056316, 39370123445405248353743, 4120204305690280446004838, 461365717080848755611811094 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..339

FORMULA

a(n) = A309148(n,n).

a(n) = (1/n) * A318477(n).

MAPLE

with(numtheory):

a:= proc(n) option remember; add(phi(n/d)*

      (-1)^(n+d)*binomial(n*d, d), d=divisors(n))/n^2

    end:

seq(a(n), n=1..20);

CROSSREFS

Main diagonal of A309148.

Cf. A304482, A318557, A318477.

Sequence in context: A079678 A233908 A089833 * A251318 A083448 A024129

Adjacent sequences:  A308664 A308665 A308666 * A308668 A308669 A308670

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Jul 14 2019

STATUS

approved

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Last modified November 21 12:28 EST 2019. Contains 329370 sequences. (Running on oeis4.)