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A048885 Number of nonisomorphic orthogonal arrays OA(4n,4n-1,2,2). 3
1, 1, 1, 5, 3, 130, 7570, 355293682 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Equivalently, number of 3-(4*n,2*n,n-1) designs.

REFERENCES

A. S. Hedayat, N. J. A. Sloane and J. Stufken, Orthogonal Arrays, Springer-Verlag, NY, 1999, see Table 7.37 page 165.

LINKS

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

Index entries for sequences related to Hadamard matrices

CROSSREFS

Cf. A007299.

Sequence in context: A180403 A267512 A230389 * A264738 A002208 A100653

Adjacent sequences:  A048882 A048883 A048884 * A048886 A048887 A048888

KEYWORD

nonn,nice,hard,more

AUTHOR

N. J. A. Sloane

EXTENSIONS

a(7) computed by N. J. A. Sloane

a(8) from Brendan McKay, Feb 11 2012

STATUS

approved

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Last modified June 29 01:21 EDT 2017. Contains 288855 sequences.