login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A035482 Number of n X n symmetric matrices each of whose rows is a permutation of 1..n. 1
1, 1, 2, 6, 96, 720, 328320, 31449600, 440952422400, 444733651353600 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

The even and odd subsequences are A036980, A036981.

LINKS

Table of n, a(n) for n=0..9.

FORMULA

a(n) = A035481(n) * n!. [From Max Alekseyev, Apr 23 2010]

EXAMPLE

a(3) = 6 because the first row is arbitrary (say, 213) and the rest is then determined. By symmetry the second row has to be 132 or 123 but in order for the third row/column to work it has to be 132.

CROSSREFS

Cf. A000438, A035481, A000315, A002860, A003090, A040082.

Sequence in context: A280117 A129364 A092287 * A322716 A007870 A081992

Adjacent sequences:  A035479 A035480 A035481 * A035483 A035484 A035485

KEYWORD

more,nonn

AUTHOR

Joshua Zucker and Joe Keane

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 3 18:22 EST 2020. Contains 338910 sequences. (Running on oeis4.)