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 1-10 of 11 results. Next

A225304 Number of nX3 -1,1 arrays such that the sum over i=1..n,j=1..3 of i*x(i,j) is zero and rows are nondecreasing (ways to put 3 thrusters pointing east or west at each of n positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

Original entry on oeis.org

0, 0, 6, 16, 0, 0, 474, 1576, 0, 0, 64700, 228876, 0, 0, 10659862, 38869960, 0, 0, 1941920508, 7211917300, 0, 0, 376790653888, 1416598649968, 0, 0, 76344225166632, 289560610889154, 0, 0, 15965033749025502, 60953934482465398, 0, 0
Offset: 1

Views

Author

R. H. Hardin May 05 2013

Keywords

Comments

Column 3 of A225310

Examples

			Some solutions for n=4
.-1.-1..1...-1.-1.-1....1..1..1...-1.-1.-1...-1.-1..1...-1.-1.-1...-1..1..1
.-1.-1.-1...-1..1..1...-1.-1.-1....1..1..1....1..1..1...-1.-1.-1...-1..1..1
.-1..1..1...-1.-1..1...-1.-1.-1....1..1..1...-1.-1.-1...-1.-1..1....1..1..1
.-1..1..1...-1..1..1....1..1..1...-1.-1.-1...-1..1..1....1..1..1...-1.-1.-1
		

A225305 Number of nX4 -1,1 arrays such that the sum over i=1..n,j=1..4 of i*x(i,j) is zero and rows are nondecreasing (ways to put 4 thrusters pointing east or west at each of n positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

Original entry on oeis.org

1, 3, 9, 31, 113, 443, 1787, 7445, 31593, 136351, 596187, 2636015, 11763569, 52920569, 239731317, 1092632909, 5006816043, 23053197067, 106601983853, 494856940025, 2305237337415, 10772988573393, 50491926308985
Offset: 1

Views

Author

R. H. Hardin May 05 2013

Keywords

Comments

Column 4 of A225310

Examples

			Some solutions for n=4
.-1..1..1..1...-1.-1.-1.-1...-1.-1..1..1...-1.-1.-1..1...-1.-1..1..1
.-1.-1.-1..1...-1.-1.-1.-1...-1.-1..1..1...-1.-1.-1..1...-1.-1.-1..1
.-1.-1.-1..1....1..1..1..1...-1.-1..1..1...-1..1..1..1...-1.-1.-1.-1
.-1..1..1..1...-1.-1..1..1...-1.-1..1..1...-1.-1..1..1....1..1..1..1
		

A225306 Number of nX5 -1,1 arrays such that the sum over i=1..n,j=1..5 of i*x(i,j) is zero and rows are nondecreasing (ways to put 5 thrusters pointing east or west at each of n positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

Original entry on oeis.org

0, 0, 12, 52, 0, 0, 5304, 26498, 0, 0, 3670280, 19472528, 0, 0, 3059952646, 16735288748, 0, 0, 2821236602612, 15715467775786, 0, 0, 2770728141476684, 15624859528160442, 0, 0, 2841704521905480868, 16166720093745817028, 0, 0
Offset: 1

Views

Author

R. H. Hardin May 05 2013

Keywords

Comments

Column 5 of A225310

Examples

			Some solutions for n=4
..1..1..1..1..1...-1.-1.-1..1..1...-1.-1.-1..1..1....1..1..1..1..1
.-1.-1.-1.-1.-1...-1.-1.-1..1..1...-1..1..1..1..1...-1..1..1..1..1
.-1.-1.-1.-1.-1....1..1..1..1..1....1..1..1..1..1...-1.-1.-1.-1.-1
..1..1..1..1..1...-1.-1.-1.-1..1...-1.-1.-1.-1.-1...-1.-1..1..1..1
		

A225307 Number of nX6 -1,1 arrays such that the sum over i=1..n,j=1..6 of i*x(i,j) is zero and rows are nondecreasing (ways to put 6 thrusters pointing east or west at each of n positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

Original entry on oeis.org

1, 3, 17, 83, 427, 2341, 13333, 77721, 461973, 2791167, 17087937, 105766229, 660771733, 4161393187, 26390549923, 168386196159, 1080202503299, 6962854947491, 45075011876699, 292931328936351, 1910374828122659
Offset: 1

Views

Author

R. H. Hardin May 05 2013

Keywords

Comments

Column 6 of A225310

Examples

			Some solutions for n=4
.-1.-1.-1.-1..1..1...-1.-1.-1.-1..1..1....1..1..1..1..1..1...-1.-1.-1..1..1..1
..1..1..1..1..1..1...-1.-1.-1.-1.-1..1...-1.-1.-1.-1.-1.-1...-1..1..1..1..1..1
.-1.-1..1..1..1..1...-1.-1.-1.-1..1..1...-1.-1.-1.-1.-1.-1...-1.-1.-1..1..1..1
.-1.-1.-1.-1.-1..1...-1..1..1..1..1..1....1..1..1..1..1..1...-1.-1.-1.-1..1..1
		

A225308 Number of n X 7 -1,1 arrays such that the sum over i=1..n, j=1..7 of i*x(i,j) is zero and rows are nondecreasing (ways to put 7 thrusters pointing east or west at each of n positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

Original entry on oeis.org

0, 0, 22, 122, 0, 0, 29638, 197440, 0, 0, 64811436, 458450486, 0, 0, 170747302728, 1245085560292, 0, 0, 497500354657954, 3694982212755606, 0, 0, 1544103180477715700, 11609994393282630090, 0, 0, 5004924971984927428464
Offset: 1

Views

Author

R. H. Hardin, May 05 2013

Keywords

Comments

Column 7 of A225310.

Examples

			Some solutions for n=4
.-1.-1.-1.-1.-1.-1.-1...-1.-1.-1.-1.-1.-1..1...-1.-1.-1..1..1..1..1
.-1.-1.-1.-1.-1..1..1...-1.-1.-1.-1.-1.-1.-1...-1.-1..1..1..1..1..1
.-1.-1.-1.-1.-1.-1..1...-1..1..1..1..1..1..1...-1.-1.-1.-1..1..1..1
..1..1..1..1..1..1..1...-1.-1.-1..1..1..1..1...-1.-1.-1.-1..1..1..1
		

Crossrefs

Cf. A225310.

A225309 Number of nX8 -1,1 arrays such that the sum over i=1..n,j=1..8 of i*x(i,j) is zero and rows are nondecreasing (ways to put 8 thrusters pointing east or west at each of n positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

Original entry on oeis.org

1, 5, 27, 175, 1165, 8221, 60007, 449693, 3437315, 26700429, 210147859, 1672294243, 13432357463, 108761156653, 886785526897, 7274670122017, 59999774031797, 497244626964801, 4138638973241695, 34580160863858515, 289947745327853737
Offset: 1

Views

Author

R. H. Hardin May 05 2013

Keywords

Comments

Column 8 of A225310

Examples

			Some solutions for n=4
.-1.-1..1..1..1..1..1..1...-1..1..1..1..1..1..1..1...-1.-1.-1.-1.-1..1..1..1
.-1.-1.-1.-1.-1..1..1..1...-1.-1.-1.-1.-1.-1..1..1....1..1..1..1..1..1..1..1
.-1.-1.-1.-1..1..1..1..1...-1.-1.-1.-1.-1..1..1..1...-1.-1.-1.-1.-1..1..1..1
.-1.-1.-1.-1..1..1..1..1...-1.-1.-1..1..1..1..1..1...-1.-1.-1.-1.-1..1..1..1
		

A225311 Number of 4 X n -1,1 arrays such that the sum over i=1..4,j=1..n of i*x(i,j) is zero and rows are nondecreasing (ways to put n thrusters pointing east or west at each of 4 positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

Original entry on oeis.org

2, 7, 16, 31, 52, 83, 122, 175, 238, 317, 410, 523, 650, 801, 970, 1165, 1380, 1625, 1892, 2193, 2518, 2879, 3268, 3697, 4154, 4655, 5188, 5767, 6380, 7043, 7742, 8495, 9286, 10133, 11022, 11971, 12962, 14017, 15118, 16285, 17500, 18785, 20120, 21529, 22990
Offset: 1

Views

Author

R. H. Hardin, May 05 2013

Keywords

Examples

			Some solutions for n=4:
.-1.-1..1..1...-1.-1..1..1...-1.-1..1..1....1..1..1..1...-1.-1..1..1
.-1.-1.-1..1...-1..1..1..1...-1.-1.-1..1...-1..1..1..1...-1.-1..1..1
..1..1..1..1....1..1..1..1...-1.-1.-1.-1...-1.-1..1..1...-1.-1..1..1
.-1.-1.-1..1...-1.-1.-1.-1....1..1..1..1...-1.-1.-1..1...-1.-1..1..1
		

Crossrefs

Row 4 of A225310.

Formula

Empirical: a(n) = a(n-1) + a(n-2) - 2*a(n-5) + a(n-8) + a(n-9) - a(n-10).
Empirical g.f.: x*(2 + 5*x + 7*x^2 + 8*x^3 + 5*x^4 + 4*x^5 + x^6 + 2*x^7 + x^8 - x^9) / ((1 - x)^4*(1 + x)^2*(1 + x^2)*(1 + x + x^2)). - Colin Barker, Sep 05 2018

A225312 Number of 5 X n -1,1 arrays such that the sum over i=1..5,j=1..n of i*x(i,j) is zero and rows are nondecreasing (ways to put n thrusters pointing east or west at each of 5 positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

Original entry on oeis.org

0, 15, 0, 113, 0, 427, 0, 1165, 0, 2591, 0, 5053, 0, 8947, 0, 14759, 0, 23017, 0, 34347, 0, 49409, 0, 68967, 0, 93813, 0, 124851, 0, 163005, 0, 209317, 0, 264843, 0, 330765, 0, 408271, 0, 498681, 0, 603315, 0, 723633, 0, 861087, 0, 1017275, 0, 1193781, 0
Offset: 1

Views

Author

R. H. Hardin, May 05 2013

Keywords

Examples

			Some solutions for n=4:
..1..1..1..1....1..1..1..1...-1..1..1..1....1..1..1..1...-1.-1.-1..1
.-1.-1.-1..1...-1.-1.-1.-1...-1..1..1..1...-1.-1.-1..1...-1..1..1..1
.-1.-1.-1.-1...-1.-1.-1.-1...-1.-1..1..1...-1.-1.-1..1...-1.-1..1..1
.-1.-1.-1..1....1..1..1..1...-1.-1.-1.-1....1..1..1..1...-1..1..1..1
..1..1..1..1...-1.-1..1..1...-1..1..1..1...-1.-1.-1..1...-1.-1.-1..1
		

Crossrefs

Row 5 of A225310.

Formula

Empirical: a(n) = 3*a(n-2) - 2*a(n-4) - 2*a(n-6) + 4*a(n-8) - 4*a(n-10) + 2*a(n-12) + 2*a(n-14) - 3*a(n-16) + a(n-18).
Empirical g.f.: x^2*(15 + 68*x^2 + 118*x^4 + 140*x^6 + 116*x^8 + 72*x^10 + 14*x^12 - 2*x^14 + x^16) / ((1 - x)^5*(1 + x)^5*(1 + x^2)^2*(1 + x^4)). - Colin Barker, Sep 05 2018

A225313 Number of 6Xn -1,1 arrays such that the sum over i=1..6,j=1..n of i*x(i,j) is zero and rows are nondecreasing (ways to put n thrusters pointing east or west at each of 6 positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

Original entry on oeis.org

0, 35, 0, 443, 0, 2341, 0, 8221, 0, 22351, 0, 51521, 0, 105247, 0, 196779, 0, 342979, 0, 565693, 0, 891247, 0, 1352233, 0, 1986519, 0, 2839617, 0, 3963039, 0, 5417341, 0, 7269805, 0, 9598181, 0, 12487593, 0, 16035169, 0, 20345971, 0, 25538619, 0
Offset: 1

Views

Author

R. H. Hardin May 05 2013

Keywords

Comments

Row 6 of A225310

Examples

			Some solutions for n=4
.-1..1..1..1...-1.-1.-1.-1...-1.-1..1..1...-1.-1.-1.-1....1..1..1..1
.-1.-1..1..1....1..1..1..1....1..1..1..1...-1.-1.-1.-1...-1..1..1..1
..1..1..1..1...-1.-1.-1.-1...-1.-1.-1..1...-1.-1.-1.-1...-1.-1.-1.-1
.-1..1..1..1...-1.-1.-1.-1...-1.-1..1..1...-1.-1.-1..1...-1.-1.-1.-1
.-1.-1.-1..1...-1.-1..1..1...-1..1..1..1....1..1..1..1....1..1..1..1
.-1.-1.-1..1....1..1..1..1...-1.-1.-1..1...-1..1..1..1...-1.-1..1..1
		

Formula

Empirical: a(n) = a(n-2) +a(n-4) -a(n-10) -2*a(n-14) +a(n-18) +a(n-20) +a(n-22) +a(n-24) -2*a(n-28) -a(n-32) +a(n-38) +a(n-40) -a(n-42)

A225314 Number of 7Xn -1,1 arrays such that the sum over i=1..7,j=1..n of i*x(i,j) is zero and rows are nondecreasing (ways to put n thrusters pointing east or west at each of 7 positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

Original entry on oeis.org

8, 87, 474, 1787, 5304, 13333, 29638, 60007, 112790, 199669, 336342, 543465, 847456, 1281681, 1887330, 2714817, 3824812, 5289809, 7195252, 9641399, 12744472, 16638757, 21477906, 27437211, 34714980, 43535143, 54148610, 66836145, 81909858
Offset: 1

Views

Author

R. H. Hardin May 05 2013

Keywords

Comments

Row 7 of A225310

Examples

			Some solutions for n=4
..1..1..1..1...-1..1..1..1...-1.-1..1..1...-1.-1.-1.-1...-1.-1.-1.-1
.-1.-1.-1..1...-1.-1.-1..1...-1.-1.-1.-1....1..1..1..1...-1.-1.-1.-1
.-1.-1.-1..1...-1.-1..1..1...-1.-1.-1..1...-1.-1.-1..1...-1.-1.-1.-1
..1..1..1..1...-1.-1.-1..1....1..1..1..1...-1.-1..1..1...-1..1..1..1
.-1.-1.-1.-1...-1..1..1..1...-1.-1..1..1...-1.-1.-1..1....1..1..1..1
..1..1..1..1...-1.-1..1..1...-1..1..1..1...-1..1..1..1....1..1..1..1
.-1.-1.-1..1...-1.-1..1..1...-1.-1.-1..1...-1.-1..1..1...-1.-1.-1.-1
		

Formula

Empirical: a(n) = 3*a(n-2) +2*a(n-3) -3*a(n-4) -5*a(n-5) +4*a(n-7) +a(n-8) -2*a(n-9) +a(n-10) +3*a(n-11) -3*a(n-13) -a(n-14) +2*a(n-15) -a(n-16) -4*a(n-17) +5*a(n-19) +3*a(n-20) -2*a(n-21) -3*a(n-22) +a(n-24)
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