cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A188409 Number of (8*n) X n binary arrays with rows in nonincreasing order, 8 ones in every column and no more than 2 ones in any row.

Original entry on oeis.org

1, 1, 9, 215, 13825, 1865715, 472211360, 205617134345, 144413237202513, 155491132440121969, 246331815235550280739, 555051611796729847585857, 1728979263188082473586904451, 7267279122553798970928760164349, 40366145202716102133415620482175732, 290962702320861139000003963988839815695
Offset: 0

Views

Author

R. H. Hardin, Mar 30 2011

Keywords

Comments

Number of n X n symmetric matrices with nonnegative integer entries and all row and column sums 8. - Andrew Howroyd, Apr 07 2020

Examples

			All solutions for 16X2
..1..1....1..1....1..1....1..1....1..1....1..1....1..1....1..0....1..1
..1..1....1..1....1..1....1..0....1..1....1..1....1..1....1..0....1..1
..1..1....1..1....1..1....1..0....1..1....1..0....1..1....1..0....1..1
..1..1....1..1....1..1....1..0....1..1....1..0....1..1....1..0....1..0
..1..1....1..1....1..1....1..0....1..1....1..0....1..0....1..0....1..0
..1..0....1..1....1..1....1..0....1..1....1..0....1..0....1..0....1..0
..1..0....1..0....1..1....1..0....1..1....1..0....1..0....1..0....1..0
..1..0....1..0....1..0....1..0....1..1....1..0....1..0....1..0....1..0
..0..1....0..1....0..1....0..1....0..0....0..1....0..1....0..1....0..1
..0..1....0..1....0..0....0..1....0..0....0..1....0..1....0..1....0..1
..0..1....0..0....0..0....0..1....0..0....0..1....0..1....0..1....0..1
..0..0....0..0....0..0....0..1....0..0....0..1....0..1....0..1....0..1
..0..0....0..0....0..0....0..1....0..0....0..1....0..0....0..1....0..1
..0..0....0..0....0..0....0..1....0..0....0..1....0..0....0..1....0..0
..0..0....0..0....0..0....0..1....0..0....0..0....0..0....0..1....0..0
..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..1....0..0

Crossrefs

Row 8 of A188403.

Extensions

a(0)=1 prepended and terms a(9) and beyond from Andrew Howroyd, Apr 06 2020

A333739 Number of n X n nonnegative integer symmetric matrices with all row and column sums equal to n.

Original entry on oeis.org

1, 1, 3, 23, 641, 62781, 22393101, 29445929253, 144413237202513, 2664174112921403401, 186127457781265060985293, 49509854244685925218197355989, 50364892612276937755557718571828543, 196663809308382999799947201118326883990475
Offset: 0

Views

Author

Andrew Howroyd, Apr 08 2020

Keywords

Crossrefs

Main diagonal of A188403.
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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