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.

Showing 1-8 of 8 results.

A359574 Array read by antidiagonals: T(m,n) is the number of m X n binary arrays with all 1's connected and a path of 1's from top row to bottom row.

Original entry on oeis.org

1, 3, 1, 6, 7, 1, 10, 28, 17, 1, 15, 88, 144, 41, 1, 21, 245, 920, 730, 99, 1, 28, 639, 5191, 9362, 3692, 239, 1, 36, 1608, 27651, 104989, 94280, 18666, 577, 1, 45, 3968, 143342, 1111283, 2075271, 947760, 94384, 1393, 1, 55, 9689, 733512, 11457514, 42972329, 40792921, 9528128, 477264, 3363, 1
Offset: 1

Views

Author

Andrew Howroyd, Jan 06 2023

Keywords

Comments

The grid has m rows and n columns.

Examples

			Array begins:
================================================================
m\n| 1   2     3       4         5           6             7
---+------------------------------------------------------------
1  | 1   3     6      10        15          21            28 ...
2  | 1   7    28      88       245         639          1608 ...
3  | 1  17   144     920      5191       27651        143342 ...
4  | 1  41   730    9362    104989     1111283      11457514 ...
5  | 1  99  3692   94280   2075271    42972329     866126030 ...
6  | 1 239 18666  947760  40792921  1642690309   64270256276 ...
7  | 1 577 94384 9528128 801218515 62618577481 4741764527414 ...
  ...
		

Crossrefs

Formula

T(m,n) = A287151(m,n) - 2*A287151(m-1,n) + A287151(m-2,n) for m > 2.

A163029 Number of n X 3 binary arrays with all 1's connected and a path of 1's from top row to bottom row.

Original entry on oeis.org

6, 28, 144, 730, 3692, 18666, 94384, 477264, 2413346, 12203374, 61707810, 312032874, 1577831334, 7978491800, 40344192708, 204005208738, 1031576601204, 5216289773894, 26376789637884, 133377373911160, 674438554337506
Offset: 1

Views

Author

R. H. Hardin, Jul 20 2009

Keywords

Crossrefs

Cf. A001333 ((n-1) X 2 arrays), A059021 (no path required).

Formula

a(n) = 7*a(n-1) - 11*a(n-2) + 6*a(n-3) + a(n-4) - 7*a(n-5) + a(n-6). [Conjectured by R. J. Mathar, Aug 11 2009]
Proof from Peter Kagey, May 08 2019: Scanning from top to bottom, there are 6 possible intermediate states that the bottom row can be in. The transitions between these states define a 6 X 6 transition matrix whose characteristic polynomial agrees with the characteristic polynomial of the above recurrence. QED
For an alternative proof see the Goodman-Strauss links. - N. J. A. Sloane, May 22 2020

A163030 Number of nX4 binary arrays with all 1s connected and a path of 1s from top row to bottom row.

Original entry on oeis.org

10, 88, 920, 9362, 94280, 947760, 9528128, 95797726, 963186740, 9684246062, 97369020768, 978984263266, 9843070964036, 98965887676178, 995039757124590, 10004498940354450, 100588944638377056, 1011358574138112578
Offset: 1

Views

Author

R. H. Hardin Jul 20 2009

Keywords

Crossrefs

Formula

Empirical: a(n)= 15*a(n-1) -59*a(n-2) +97*a(n-3) -19*a(n-4) -210*a(n-5) +222*a(n-6) +22*a(n-7) -113*a(n-8) +7*a(n-9) -71*a(n-10) +13*a(n-11) +a(n-12). [From R. J. Mathar, Aug 11 2009]
For a proof see the Goodman-Strauss links. - N. J. A. Sloane, May 22 2020

A163031 Number of n X 5 binary arrays with all 1s connected and a path of 1s from top row to bottom row.

Original entry on oeis.org

15, 245, 5191, 104989, 2075271, 40792921, 801218515, 15736428305, 309080891641, 6070750256417, 119237718452471, 2341990743046197, 45999883370408813, 903500281246849523, 17745974522766912147, 348555078644003475079
Offset: 1

Views

Author

R. H. Hardin, Jul 20 2009

Keywords

Crossrefs

Column 5 of A359574.

Formula

For a formula see the Goodman-Strauss links. - N. J. A. Sloane, May 22 2020

A163032 Number of n X 6 binary arrays with all 1s connected and a path of 1s from top row to bottom row.

Original entry on oeis.org

21, 639, 27651, 1111283, 42972329, 1642690309, 62618577481, 2385542862643, 90870669971589, 3461426734215747, 131852221160935917, 5022507165784282263, 191317198008071782069, 7287650933960562176059, 277601073047629123048799, 10574375404737019213183521
Offset: 1

Views

Author

R. H. Hardin, Jul 20 2009

Keywords

Crossrefs

Column 6 of A359574.

Formula

For a formula see the Goodman-Strauss links. - N. J. A. Sloane, May 22 2020

Extensions

Terms a(11) and beyond from Andrew Howroyd, Jan 06 2023

A163033 Number of n X 7 binary arrays with all 1s connected and a path of 1s from top row to bottom row.

Original entry on oeis.org

28, 1608, 143342, 11457514, 866126030, 64270256276, 4741764527414, 349218174915782, 25705066468491048, 1891784307926020004, 139221054649194353330, 10245491277444041078478, 753978851322477798813560, 55486218768479949691575070, 4083297106688472106576343018
Offset: 1

Views

Author

R. H. Hardin, Jul 20 2009

Keywords

Crossrefs

Column 7 of A359574.

Formula

For a formula see the Goodman-Strauss links. - N. J. A. Sloane, May 22 2020

Extensions

Terms a(9) and beyond from Andrew Howroyd, Jan 06 2023

A163034 Number of n X 8 binary arrays with all 1s connected and a path of 1s from top row to bottom row.

Original entry on oeis.org

36, 3968, 733512, 116648336, 17234589848, 2481063626002, 353883736096148, 50301538415794232, 7140496309756236272, 1013108119964866470278, 143713897214120554999482, 20384925139787491684594856, 2891390846534568194577474354, 410109224260079991594244323232
Offset: 1

Views

Author

R. H. Hardin, Jul 20 2009

Keywords

Crossrefs

Column 8 of A359574.

Formula

For a formula see the Goodman-Strauss links. - N. J. A. Sloane, May 22 2020

Extensions

Terms a(8) and beyond from Andrew Howroyd, Jan 06 2023

A163035 Number of nX9 binary arrays with all 1s connected and a path of 1s from top row to bottom row.

Original entry on oeis.org

45, 9689, 3730303, 1180202569, 340759985173, 95151328370775
Offset: 1

Views

Author

R. H. Hardin Jul 20 2009

Keywords

Crossrefs

Formula

For a formula see the Goodman-Strauss links. - N. J. A. Sloane, May 22 2020
Showing 1-8 of 8 results.