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A238838 Number of 2n X 2n addition squares in which every digram (s,s;), s' != s, appears once horizontally and once vertically. 1
2, 48, 5760, 5806080, 75246796800, 1780537083494400, 115939740156316876800, 19864514173849162481664000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..8.

Gilbert, E. N., Latin squares which contain no repeated digrams, SIAM Rev. 7 1965 189--198. MR0179095 (31 #3346).

FORMULA

a(n) = (2*n)!*A141599(n)^2/phi(n).

CROSSREFS

Cf. A000315, A002860, A000010, A141599.

Sequence in context: A087085 A067626 A053071 * A002820 A196448 A053290

Adjacent sequences:  A238835 A238836 A238837 * A238839 A238840 A238841

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, Mar 15 2014

STATUS

approved

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Last modified August 10 19:52 EDT 2020. Contains 336381 sequences. (Running on oeis4.)