

A238838


Number of 2n X 2n addition squares in which every digram (s,s;), s' != s, appears once horizontally and once vertically.


1




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 189198. 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



