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

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A260340 Triangle read by rows: T(n,k) = number of sets of linear n-ads in k variables. 5
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 6, 1, 1, 1, 1, 22, 22, 1, 1, 1, 1, 130, 550, 130, 1, 1, 1, 1, 822, 16700, 16700, 822, 1, 1, 1, 1, 6202, 703297, 3330915, 703297, 6202, 1, 1, 1, 1, 52552, 38135272, 957659906, 957659906, 38135272, 52552, 1, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,13

COMMENTS

T(n,k) is the number of nonequivalent n X n binary matrices with k ones in every row and column up to permutation of rows. - Andrew Howroyd, Apr 18 2020

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..230 (rows 0..20)

P. A. MacMahon, Combinations derived from m identical sets of n different letters and their connexion with general magic squares, Proc. London Math. Soc., 17 (1917), 25-41.

FORMULA

T(n,k) = T(n,n-k). - Andrew Howroyd, Apr 18 2020

EXAMPLE

Triangle begins:

  1;

  1, 1;

  1, 1,    1;

  1, 1,    1,      1;

  1, 1,    6,      1,       1;

  1, 1,   22,     22,       1,      1;

  1, 1,  130,    550,     130,      1,    1;

  1, 1,  822,  16700,   16700,    822,    1, 1;

  1, 1, 6202, 703297, 3330915, 703297, 6202, 1, 1;

  ...

CROSSREFS

Columns k=0..4 are A000012, A000012, A002137, A333899, A333900.

Row sums are A333891.

Cf. A008300, A133687, A257463.

Sequence in context: A339747 A293901 A324891 * A040037 A344877 A333461

Adjacent sequences:  A260337 A260338 A260339 * A260341 A260342 A260343

KEYWORD

nonn,tabl

AUTHOR

N. J. A. Sloane, Jul 30 2015

EXTENSIONS

Extended to include k=0 and more terms added by Andrew Howroyd, Apr 18 2020

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 November 30 13:07 EST 2021. Contains 349419 sequences. (Running on oeis4.)