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A318625 Number of 4-member subsets of [4*n] whose elements sum to a multiple of n. 2
0, 1, 38, 165, 460, 969, 1782, 2925, 4508, 6545, 9158, 12341, 16236, 20825, 26262, 32509, 39740, 47905, 57190, 67525, 79116, 91881, 106038, 121485, 138460, 156849, 176902, 198485, 221868, 246905, 273878, 302621, 333436, 366145, 401062, 437989, 477260, 518665 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..10000

Index entries for linear recurrences with constant coefficients, signature (2,0,-2,2,-2,0,2,-1).

FORMULA

G.f.: x*(4*x^7+27*x^6+100*x^5+123*x^4+132*x^3+89*x^2+36*x+1) / ((x^2+1) *(x+1)^2 *(x-1)^4).

EXAMPLE

a(2) = 38: {1,2,3,4}, {1,2,3,6}, {1,2,3,8}, {1,2,4,5}, {1,2,4,7}, {1,2,5,6}, {1,2,5,8}, {1,2,6,7}, {1,2,7,8}, {1,3,4,6}, {1,3,4,8}, {1,3,5,7}, {1,3,6,8}, {1,4,5,6}, {1,4,5,8}, {1,4,6,7}, {1,4,7,8}, {1,5,6,8}, {1,6,7,8}, {2,3,4,5}, {2,3,4,7}, {2,3,5,6}, {2,3,5,8}, {2,3,6,7}, {2,3,7,8}, {2,4,5,7}, {2,4,6,8}, {2,5,6,7}, {2,5,7,8}, {3,4,5,6}, {3,4,5,8}, {3,4,6,7}, {3,4,7,8}, {3,5,6,8}, {3,6,7,8}, {4,5,6,7}, {4,5,7,8}, {5,6,7,8}.

CROSSREFS

Row n=4 of A318557.

Sequence in context: A251253 A224739 A135176 * A281208 A100167 A100168

Adjacent sequences:  A318622 A318623 A318624 * A318626 A318627 A318628

KEYWORD

nonn,easy

AUTHOR

Alois P. Heinz, Aug 30 2018

STATUS

approved

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Last modified July 25 21:44 EDT 2021. Contains 346294 sequences. (Running on oeis4.)