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A147774 Number of equivalence classes of normalized Hadamard matrices of order 4n with respect to permutations of rows and columns. 0
1, 1, 2, 118, 6520, 43966313 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Number of equivalence classes N(k) = {1, 1, 1, 1, 2, 118, 6520, 43966313} for order k = {1, 2, 4, 8, 12, 16, 20, 24}, (see Theorem 2 at the Hadamard matrices project results link). Note that N(24) = a(6) = 43966313 is a prime.

LINKS

Table of n, a(n) for n=1..6.

Hadamard Matrices Project. Results (in Russian) [broken link]

Eric Weisstein's World of Mathematics, Hadamard Matrix

CROSSREFS

Cf. A007299 = Number of Hadamard matrices of order 4n.

Sequence in context: A042681 A024243 A307094 * A013470 A013511 A013507

Adjacent sequences:  A147771 A147772 A147773 * A147775 A147776 A147777

KEYWORD

more,nonn

AUTHOR

Alexander Adamchuk, Nov 12 2008

STATUS

approved

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Last modified September 24 09:10 EDT 2021. Contains 347630 sequences. (Running on oeis4.)