[go: up one dir, main page]
login
The OEIS is supported by the many generous donors to the OEIS Foundation.
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A333888
Number of non-isomorphic n X n nonnegative integer symmetric matrices with all row and column sums equal to 3 up to permutations of rows and columns.
1
1, 1, 2, 5, 12, 29, 79, 225, 677, 2141, 7121, 24693, 89117, 333312, 1288949, 5140039, 21094565, 88931387, 384544989, 1703083332, 7715920544, 35720666818, 168809971994, 813633173238, 3996247863791, 19986651995983, 101715962631912, 526405121697307, 2768690275913665, 14791474244527076, 80224577967948446
(list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
Table of n, a(n) for n=0..30.
EXAMPLE
The a(2) = 2 matrices are:
[0 3] [1 2]
[3 0] [2 1]
CROSSREFS
Column k=3 of A333737.
Sequence in context: A261234 A368984 A324787 * A228516 A101411 A042789
Adjacent sequences: A333885 A333886 A333887 * A333889 A333890 A333891
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Apr 08 2020
STATUS
approved

Lookup Welcome Wiki Register Music Plot 2 Demos Index WebCam Contribute Format Style Sheet Transforms Superseeker Recents
The OEIS Community
Maintained by The OEIS Foundation Inc.
Last modified October 4 21:02 EDT 2024. Contains 376525 sequences.
License Agreements, Terms of Use, Privacy Policy