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 1-5 of 5 results.

A211905 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any horizontal or vertical neighbor, and containing the value n(n+1)/2-2.

Original entry on oeis.org

0, 2, 10, 34, 86, 181, 337, 575, 919, 1396, 2036, 2872, 3940, 5279, 6931, 8941, 11357, 14230, 17614, 21566, 26146, 31417, 37445, 44299, 52051, 60776, 70552, 81460, 93584, 107011, 121831, 138137, 156025, 175594, 196946, 220186, 245422, 272765, 302329
Offset: 1

Views

Author

R. H. Hardin, Apr 25 2012

Keywords

Comments

Column 1 of A211910.

Examples

			Some solutions for n=4:
..0........0........0........0........0........0........0........0
..1.2......1.2......1.2......1.2......1.2......1.2......1.2......1.2
..3.4.5....3.4.5....3.0.4....3.4.5....3.4.5....3.4.3....3.4.5....3.4.5
..6.0.7.8..6.7.8.7..5.6.7.8..6.7.4.8..6.7.8.4..5.6.7.8..6.1.7.8..6.7.0.8
		

Formula

Empirical: a(n) = (1/8)*n^4 + (1/4)*n^3 - (9/8)*n^2 + (3/4)*n + 1 for n>1.

A211906 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any horizontal or vertical neighbor, and containing the value n(n+1)/2-3.

Original entry on oeis.org

0, 2, 30, 418, 3006, 14201, 51157, 152650, 396538, 926011, 1987151, 3980637, 7530745, 13575108, 23479016, 39178351, 63355567, 99653440, 152931628, 229571396, 337834176, 488279947, 694251735
Offset: 1

Views

Author

R. H. Hardin Apr 25 2012

Keywords

Comments

Column 2 of A211910

Examples

			Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.2......1.2......1.2......1.2......1.2......1.2
..3.4.5....3.4.5....3.4.5....3.4.2....3.4.5....3.4.5....2.3.4....3.4.5
..6.7.0.8..6.0.1.7..6.3.7.8..5.6.7.3..1.5.6.7..6.2.7.5..5.6.0.7..6.2.6.7
		

Formula

Empirical: a(n) = (1/128)*n^8 + (1/32)*n^7 - (29/192)*n^6 - (5/16)*n^5 + (193/128)*n^4 - (25/96)*n^3 - (275/96)*n^2 + (49/24)*n + 1 for n>1

A211907 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any horizontal or vertical neighbor, and containing the value n(n+1)/2-4.

Original entry on oeis.org

0, 0, 41, 2385, 55822, 637721, 4639742, 24871596, 106911695, 388681117, 1238600816, 3548005682, 9306274551
Offset: 1

Views

Author

R. H. Hardin Apr 25 2012

Keywords

Comments

Column 3 of A211910

Examples

			Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.0......1.2......1.2......1.0......1.2......1.0
..3.4.5....0.3.2....2.3.4....3.4.2....3.4.3....2.3.4....3.1.4....2.1.3
..6.3.0.6..4.5.3.6..1.0.5.6..0.3.5.6..4.5.2.6..5.2.6.5..5.6.3.4..1.4.5.6
		

A211908 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any horizontal or vertical neighbor, and containing the value n(n+1)/2-5.

Original entry on oeis.org

0, 0, 42, 6927, 605769, 18239150, 281228042, 2788818593, 20221781939
Offset: 1

Views

Author

R. H. Hardin, Apr 25 2012

Keywords

Comments

Column 4 of A211910.

Examples

			Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.2......1.2......1.2......1.2......1.2......1.2
..3.4.5....3.1.4....2.0.3....3.4.1....0.3.4....3.4.3....3.4.5....2.3.4
..4.5.6.2..5.6.1.4..4.1.5.3..2.5.6.4..1.5.6.3..5.3.0.4..5.1.3.4..3.4.5.6
		

Crossrefs

Cf. A211910.

A211909 Number of lower triangular n X n arrays colored with integers 0 upwards introduced in row major order, with no element equal to any horizontal or vertical neighbor, and containing the value n(n+1)/2-6.

Original entry on oeis.org

0, 0, 42, 11296, 3997836, 350026718, 12075054829, 228741733963
Offset: 1

Views

Author

R. H. Hardin Apr 25 2012

Keywords

Comments

Column 5 of A211910

Examples

			Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.2......1.2......1.2......1.0......1.2......1.2
..2.3.2....0.3.0....0.3.4....3.4.3....2.1.3....2.3.2....2.3.2....3.0.4
..4.1.4.0..4.5.2.6..3.0.2.0..5.0.5.3..4.0.4.3..4.2.0.1..3.4.3.1..4.5.2.0
		
Showing 1-5 of 5 results.