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 A362291 Number of pairs of disjoint subsets of 1..n^2 of size 2*floor(n/2) having equal sum. 1
 1, 2, 68, 26098, 1408886, 12369296230, 673890139470, 33193434883028584 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..8. FORMULA a(n) = A362280(n)/((m!)^2 * (n^2-2m)!), where m = 2*floor(n/2). PROG (Python) from math import factorial from itertools import combinations as C def a(n): E = [i for i in range(1, n**2+1)] m = n if n%2 == 0 else n-1 return sum(1 for u in C(E, 2*m) for t in C(u, m) if 2*sum(t)==sum(u)) print([a(n) for n in range(1, 5)]) CROSSREFS Cf. A052928, A362280. Sequence in context: A283038 A264457 A246744 * A364854 A041577 A180085 Adjacent sequences: A362288 A362289 A362290 * A362292 A362293 A362294 KEYWORD nonn,hard,more AUTHOR Michael S. Branicky, Apr 14 2023 EXTENSIONS a(6)-a(7) from Martin Ehrenstein, Apr 16 2023 a(8) from Martin Ehrenstein, Apr 25 2023 STATUS approved

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Last modified September 17 23:36 EDT 2024. Contains 375991 sequences. (Running on oeis4.)