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.

Previous Showing 11-19 of 19 results.

A240284 T(n,k)=Number of nXk 0..3 arrays with no element equal to one plus the sum of elements to its left or two plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest, modulo 4.

Original entry on oeis.org

1, 2, 2, 2, 8, 3, 4, 19, 19, 4, 4, 76, 80, 38, 7, 8, 181, 570, 262, 114, 10, 8, 741, 2574, 3457, 1461, 251, 15, 16, 1779, 20764, 28654, 33183, 5443, 612, 24, 16, 7308, 97348, 443168, 484146, 218658, 24490, 1656, 35, 32, 17561, 802835, 3980245, 13490093, 5646644
Offset: 1

Views

Author

R. H. Hardin, Apr 03 2014

Keywords

Comments

Table starts
..1....2.......2.........4............4.............8..............8
..2....8......19........76..........181...........741...........1779
..3...19......80.......570.........2574.........20764..........97348
..4...38.....262......3457........28654........443168........3980245
..7..114....1461.....33183.......484146......13490093......224906182
.10..251....5443....218658......5646644.....281488213.....8597299482
.15..612...24490...1851080.....88953626....8199368365...463717321235
.24.1656..117962..15760838...1357879302..225885684501.23104690637116
.35.3758..459193.110599613..17350066110.5291794810655
.54.9630.2147788.945852472.272318368893

Examples

			Some solutions for n=4 k=4
..3..1..3..3....3..3..1..1....3..1..3..3....3..1..3..1....3..1..3..1
..3..1..3..2....3..2..1..2....3..1..0..0....3..2..0..1....2..2..2..0
..3..1..3..2....2..0..2..2....2..2..2..0....3..2..3..2....2..0..0..1
..2..2..2..0....3..1..0..0....3..1..0..0....2..2..3..3....3..3..0..2
		

Crossrefs

Column 1 is A159288
Row 1 is A016116

Formula

Empirical for column k:
k=1: a(n) = a(n-2) +2*a(n-3)
k=2: [order 15]
Empirical for row n:
n=1: a(n) = 2*a(n-2)
n=2: a(n) = 12*a(n-2) -24*a(n-4) +31*a(n-6) -16*a(n-8)
n=3: [order 48] for n>51

A241397 T(n,k)=Number of nXk 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest or one plus the sum of the elements antidiagonally to its northeast, modulo 4.

Original entry on oeis.org

2, 2, 3, 4, 5, 4, 6, 9, 13, 7, 8, 23, 29, 28, 10, 14, 44, 85, 97, 64, 15, 20, 93, 201, 480, 340, 142, 24, 30, 204, 689, 1657, 2780, 1156, 318, 35, 48, 368, 1929, 8697, 15339, 17211, 4068, 726, 54, 70, 761, 4068, 31654, 129985, 160947, 102782, 14763, 1634, 83, 108
Offset: 1

Views

Author

R. H. Hardin, Apr 20 2014

Keywords

Comments

Table starts
..2....2......4........6..........8..........14..........20.........30
..3....5......9.......23.........44..........93.........204........368
..4...13.....29.......85........201.........689........1929.......4068
..7...28.....97......480.......1657........8697.......31654......92204
.10...64....340.....2780......15339......129985......667050....2949778
.15..142...1156....17211.....160947.....2234804....18589398..134190457
.24..318...4068...102782....1622867....39781828...541660724.7518340973
.35..726..14763...645484...18627122...821631365.21331876978
.54.1634..52950..3936420..196990531.16108803423
.83.3695.190950.24633252.2356216195

Examples

			Some solutions for n=4 k=4
..3..2..3..3....3..2..2..2....2..3..3..2....2..3..3..2....2..3..3..2
..1..2..1..2....2..1..0..0....2..1..2..0....2..3..2..2....1..3..1..2
..3..2..0..0....3..1..2..0....3..0..0..2....2..0..0..3....1..2..0..2
..1..0..0..0....3..2..0..0....2..0..1..0....2..1..1..3....3..2..2..2
		

Crossrefs

Column 1 is A159288(n+1)
Row 1 is A239851

Formula

Empirical for column k:
k=1: a(n) = a(n-2) +2*a(n-3)
k=2: [order 38]
Empirical for row n:
n=1: a(n) = a(n-2) +2*a(n-3)
n=2: [order 22] for n>23

A241054 T(n,k)=Number of nXk 0..3 arrays with no element equal to one plus the sum of elements to its left or zero plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest or one plus the sum of the elements antidiagonally to its northeast, modulo 4.

Original entry on oeis.org

2, 3, 2, 4, 3, 4, 7, 2, 4, 6, 10, 10, 3, 6, 8, 15, 18, 24, 6, 8, 14, 24, 18, 60, 64, 6, 12, 20, 35, 46, 93, 163, 132, 15, 13, 30, 54, 58, 297, 280, 598, 690, 31, 20, 48, 83, 102, 507, 1423, 1392, 3411, 2142, 58, 28, 70, 124, 173, 1264, 4167, 10921, 13273, 11283, 7144, 170, 38
Offset: 1

Views

Author

R. H. Hardin, Apr 15 2014

Keywords

Comments

Table starts
..2..3...4.....7......10........15..........24..........35..........54
..2..3...2....10......18........18..........46..........58.........102
..4..4...3....24......60........93.........297.........507........1264
..6..6...6....64.....163.......280........1423........4167.......13389
..8..8...6...132.....598......1392.......10921.......72769......370453
.14.12..15...690....3411.....13273......189680.....2667280....18820225
.20.13..31..2142...11283.....89910.....1511923....30914092...376386754
.30.20..58..7144...72578...1128052....35582068..1432670661.26960360814
.48.28.170.30662..404421..13331118...776191453.62057946683
.70.38.388.95669.2220973.128026529.14877945554

Examples

			Some solutions for n=4 k=4
..3..2..3..3....3..3..2..2....3..2..3..2....3..3..2..3....3..3..2..2
..2..1..1..0....2..1..1..3....2..1..1..0....2..1..1..0....2..1..1..3
..2..0..2..0....3..3..2..2....2..1..3..0....3..3..2..2....3..3..2..3
..2..0..0..0....2..0..2..0....2..1..2..0....3..1..0..0....2..1..2..3
		

Crossrefs

Column 1 is A239851
Row 1 is A159288(n+1)

Formula

Empirical for column k:
k=1: a(n) = a(n-2) +2*a(n-3)
k=2: a(n) = 2*a(n-2) -a(n-4) +a(n-5) -a(n-7) +a(n-8) +a(n-11) for n>15
Empirical for row n:
n=1: a(n) = a(n-2) +2*a(n-3)
n=2: [order 15] for n>17
n=3: [order 70] for n>85

A159287 Expansion of x^2/(1-x^2-2*x^3).

Original entry on oeis.org

0, 0, 1, 0, 1, 2, 1, 4, 5, 6, 13, 16, 25, 42, 57, 92, 141, 206, 325, 488, 737, 1138, 1713, 2612, 3989, 6038, 9213, 14016, 21289, 32442, 49321, 75020, 114205, 173662, 264245, 402072, 611569, 930562, 1415713, 2153700, 3276837, 4985126, 7584237, 11538800
Offset: 0

Views

Author

Creighton Dement, Apr 08 2009

Keywords

Comments

A floretion-generated sequence: 'i + 0.5('ij' + 'ik' + 'ji' + 'jk' + 'ki' + 'kj').
From Greg Dresden, Nov 15 2024: (Start)
a(n) is the number of ways to tile a 2 X (n+1) board with L-shaped trominos and S-shaped quadrominos, where the first tile must be an upright L. For example, here are the a(7)=4 ways to tile a 2 X 8 board:
| | | | | | | | | | | |
|_|_||__|___| |_|___|||___|
| | | | | | | | | | | |
|_|_|_|___|| |__|___||__|_| (End)

Crossrefs

Essentially the same as A052947.

Programs

Formula

G.f.: x^2/(1-x^2-2*x^3).
a(n) = A052947(n-2). - R. J. Mathar, Nov 10 2009
a(n) = a(n-2) + 2*a(n-3). - Wesley Ivan Hurt, May 23 2023
From Greg Dresden, Nov 17 2024: (Start)
a(2*n+1) = 2*a(n)^2 + 2*a(n+1)*a(n+2).
a(3*n+1) = Sum_{i=1..n} a(3*i-2)*2^(n-i). (End)

A240792 T(n,k)=Number of nXk 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest or zero plus the sum of the elements antidiagonally to its northeast, modulo 4.

Original entry on oeis.org

2, 3, 3, 4, 4, 4, 7, 5, 5, 7, 10, 10, 8, 10, 10, 15, 14, 19, 27, 13, 15, 24, 24, 34, 37, 49, 14, 24, 35, 53, 82, 132, 85, 50, 30, 35, 54, 70, 278, 552, 460, 142, 89, 32, 54, 83, 140, 669, 2277, 2009, 1130, 386, 115, 36, 83, 124, 237, 1969, 11588, 15611, 6993, 6393, 979, 182
Offset: 1

Views

Author

R. H. Hardin, Apr 12 2014

Keywords

Comments

Table starts
..2..3...4....7.....10......15.........24.........35..........54.........83
..3..4...5...10.....14......24.........53.........70.........140........237
..4..5...8...19.....34......82........278........669........1969.......3553
..7.10..27...37....132.....552.......2277......11588.......35799.....109054
.10.13..49...85....460....2009......15611......90831......522104....2386511
.15.14..50..142...1130....6993......92681.....983289.....7075546...64616034
.24.30..89..386...6393...69732....1691066...33021579...408482271.5524873850
.35.32.115..979..22255..398128...16946464..651434319.13673101597
.54.36.182.1988..62705.1646410..117913446.8338435721
.83.67.289.5128.252760.9472037.1022475213

Examples

			Some solutions for n=4 k=4
..3..2..3..2....3..2..3..2....3..2..3..2....3..2..3..3....3..2..3..3
..3..2..3..2....3..2..1..2....3..2..1..1....3..2..1..1....3..2..1..1
..2..2..0..3....2..2..0..2....2..2..3..1....2..2..2..2....2..2..3..2
..2..0..2..2....3..1..3..2....3..1..3..2....3..1..0..2....3..1..3..1
		

Crossrefs

Row and column 1 are A159288(n+1)

Formula

Empirical for column k:
k=1: a(n) = a(n-2) +2*a(n-3)
k=2: [order 17] for n>19
k=3: [order 76] for n>87
Empirical for row n:
n=1: a(n) = a(n-2) +2*a(n-3)
n=2: [order 17] for n>21

A240376 T(n,k)=Number of nXk 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest, modulo 4.

Original entry on oeis.org

2, 3, 3, 4, 11, 4, 7, 21, 21, 7, 10, 67, 75, 67, 10, 15, 155, 450, 450, 155, 15, 24, 353, 1729, 5161, 1729, 353, 24, 35, 998, 7233, 36398, 36398, 7233, 998, 35, 54, 2256, 36148, 271764, 486179, 271764, 36148, 2256, 54, 83, 5639, 139855, 2492182, 6436979
Offset: 1

Views

Author

R. H. Hardin, Apr 04 2014

Keywords

Comments

Table starts
..2.....3.......4..........7...........10............15.............24
..3....11......21.........67..........155...........353............998
..4....21......75........450.........1729..........7233..........36148
..7....67.....450.......5161........36398........271764........2492182
.10...155....1729......36398.......486179.......6436979......110122847
.15...353....7233.....271764......6436979.....169838571.....5145071133
.24...998...36148....2492182....110122847....5145071133...296413962369
.35..2256..139855...17380978...1403151574..121626491919.12947745036751
.54..5639..645733..143489019..20729739995.3384817934297
.83.14624.2919837.1182292032.314460587672

Examples

			Some solutions for n=4 k=4
..3..2..3..3....3..3..2..3....2..2..3..2....3..3..2..3....3..2..3..3
..2..0..1..2....3..2..0..3....2..1..1..0....3..1..2..1....2..1..1..2
..3..1..2..1....2..0..2..0....3..1..2..1....2..2..2..2....3..3..2..0
..2..1..1..2....3..1..0..2....2..0..2..2....2..0..0..0....2..1..2..0
		

Crossrefs

Column 1 is A159288(n+1)

Formula

Empirical for column k:
k=1: a(n) = a(n-2) +2*a(n-3)
k=2: [order 15] for n>17

A240406 T(n,k)=Number of nXk 0..3 arrays with no element equal to one plus the sum of elements to its left or three plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest, modulo 4.

Original entry on oeis.org

1, 2, 2, 3, 5, 3, 4, 14, 14, 4, 7, 24, 77, 24, 7, 10, 77, 235, 235, 77, 10, 15, 182, 1381, 1304, 1381, 182, 15, 24, 397, 5566, 13648, 13648, 5566, 397, 24, 35, 1164, 21413, 98837, 257243, 98837, 21413, 1164, 35, 54, 2626, 114951, 692520, 3366314, 3366314, 692520
Offset: 1

Views

Author

R. H. Hardin, Apr 04 2014

Keywords

Comments

Table starts
..1....2.......3.........4............7............10............15
..2....5......14........24...........77...........182...........397
..3...14......77.......235.........1381..........5566.........21413
..4...24.....235......1304........13648.........98837........692520
..7...77....1381.....13648.......257243.......3366314......43820839
.10..182....5566.....98837......3366314......80283637....1935005419
.15..397...21413....692520.....43820839....1935005419...85908009949
.24.1164..114951...6686074....766539340...62076655091.5128168982319
.35.2626..447479..47001423...9754760605.1450984782112
.54.6439.1942846.368795251.139442821024

Examples

			Some solutions for n=4 k=4
..2..1..1..2....2..2..2..2....2..1..2..1....2..2..2..1....2..2..2..1
..3..1..3..3....3..3..0..0....3..3..0..1....3..3..0..1....3..3..0..1
..2..0..0..1....2..2..0..0....2..2..0..0....2..2..2..0....2..2..0..0
..3..3..2..2....3..1..0..2....3..3..0..0....3..3..0..0....3..1..0..3
		

Crossrefs

Column 1 is A159288

Formula

Empirical for column k:
k=1: a(n) = a(n-2) +2*a(n-3)
k=2: [order 15]

A159285 Expansion of (1+3*x)/(1-x^2-2*x^3).

Original entry on oeis.org

1, 3, 1, 5, 7, 7, 17, 21, 31, 55, 73, 117, 183, 263, 417, 629, 943, 1463, 2201, 3349, 5127, 7751, 11825, 18005, 27327, 41655, 63337, 96309, 146647, 222983, 339265, 516277, 785231, 1194807, 1817785, 2765269, 4207399, 6400839, 9737937, 14815637
Offset: 0

Views

Author

Creighton Dement, Apr 08 2009

Keywords

Comments

A floretion-generated sequence: 'i + 0.5('ij' + 'ik' + 'ji' + 'jk' + 'ki' + 'kj')

Crossrefs

Programs

  • Magma
    I:=[1,3,1]; [n le 3 select I[n] else Self(n-2) + 2*Self(n-3): n in [1..30]]; // G. C. Greubel, Jun 27 2018
  • Mathematica
    LinearRecurrence[{0, 1, 2}, {1, 3, 1}, 50] (* G. C. Greubel, Jun 27 2018 *)
    CoefficientList[Series[(1+3x)/(1-x^2-2x^3),{x,0,40}],x] (* Harvey P. Dale, Jan 21 2019 *)
  • PARI
    a(n)=([0,1,0; 0,0,1; 2,1,0]^n*[1;3;1])[1,1] \\ Charles R Greathouse IV, Oct 03 2016
    

Formula

a(n) = A052947(n) + 3*A052947(n-1). - R. J. Mathar, Mar 23 2023

A159286 Expansion of (x-1)^2/(1-x^2-2*x^3).

Original entry on oeis.org

1, -2, 2, 0, -2, 4, -2, 0, 6, -4, 6, 8, -2, 20, 14, 16, 54, 44, 86, 152, 174, 324, 478, 672, 1126, 1628, 2470, 3880, 5726, 8820, 13486, 20272, 31126, 47244, 71670, 109496, 166158, 252836, 385150, 585152
Offset: 0

Views

Author

Creighton Dement, Apr 08 2009

Keywords

Comments

A floretion-generated sequence: 'i + 0.5('ij' + 'ik' + 'ji' + 'jk' + 'ki' + 'kj').

Crossrefs

Programs

  • Magma
    I:=[1, -2, 2]; [n le 3 select I[n] else Self(n-2) + 2*Self(n-3): n in [1..30]]; // G. C. Greubel, Jun 27 2018
  • Mathematica
    CoefficientList[Series[(x-1)^2/(1-x^2-2*x^3),{x,0,40}],x] (* or *) LinearRecurrence[{0,1,2},{1,-2,2},40]  (* Harvey P. Dale, Apr 24 2011 *)
  • PARI
    a(n)=([0,1,0; 0,0,1; 2,1,0]^n*[1;-2;2])[1,1] \\ Charles R Greathouse IV, Oct 03 2016
    

Formula

a(n) = A159288(n) - 3*A159287(n+1). - R. J. Mathar, Apr 10 2009
a(1)=1, a(2)=-2, a(3)=2, a(n) = 1*a(n-2) + 2*a(n-3) for n >= 3. - Harvey P. Dale, Apr 24 2011
a(n) = A078026(n)-A078026(n-1). - R. J. Mathar, Mar 23 2023
Previous Showing 11-19 of 19 results.