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 19 results. Next

A159284 Expansion of x*(1+x)/(1-x^2-2*x^3).

Original entry on oeis.org

0, 1, 1, 1, 3, 3, 5, 9, 11, 19, 29, 41, 67, 99, 149, 233, 347, 531, 813, 1225, 1875, 2851, 4325, 6601, 10027, 15251, 23229, 35305, 53731, 81763, 124341, 189225, 287867, 437907, 666317, 1013641, 1542131, 2346275, 3569413, 5430537
Offset: 0

Views

Author

Creighton Dement, Apr 08 2009

Keywords

Comments

a(n) is the number of composition of n+1 into parts congruent to 0 or 2 modulo 3. - Joerg Arndt, Apr 21 2025

Crossrefs

Programs

  • Magma
    I:=[0,1,1]; [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
    CoefficientList[Series[x (1+x)/(1-x^2-2x^3),{x,0,50}],x] (* or *) LinearRecurrence[ {0,1,2},{0,1,1},50] (* Harvey P. Dale, Jul 16 2013 *)
  • PARI
    a(n)=([0,1,0; 0,0,1; 2,1,0]^n*[0;1;1])[1,1] \\ Charles R Greathouse IV, Oct 03 2016
    

Formula

a(n) = abs(A078028(n-1)). - R. J. Mathar, Jul 05 2012
a(n) = a(n-2) + 2*a(n-3), a(0)=0, a(1) = a(2) =1. - G. C. Greubel, Apr 30 2017
a(n) = A052947(n-1)+A052947(n-2). - R. J. Mathar, Mar 23 2023

Extensions

Deleted certain dangerous or potentially dangerous links. - N. J. A. Sloane, Jan 30 2021

A241255 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 one 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, 2, 4, 5, 4, 7, 4, 17, 6, 10, 10, 13, 39, 8, 15, 12, 34, 47, 87, 14, 24, 22, 71, 120, 174, 212, 20, 35, 41, 135, 446, 545, 606, 488, 30, 54, 59, 356, 1202, 3404, 2570, 2111, 1134, 48, 83, 120, 734, 3822, 11700, 25190, 13328, 6647, 2644, 70, 124, 171, 1705, 11428
Offset: 1

Views

Author

R. H. Hardin, Apr 18 2014

Keywords

Comments

Table starts
..2....3.....4.......7........10.........15.........24.........35.........54
..2....5.....4......10........12.........22.........41.........59........120
..4...17....13......34........71........135........356........734.......1705
..6...39....47.....120.......446.......1202.......3822......11428......35540
..8...87...174.....545......3404......11700......50281.....252069.....959723
.14..212...606....2570.....25190.....124372.....752717....6264519...34987493
.20..488..2111...13328....225191....1558957...13138271..205823368.1596727720
.30.1134..6647...70264...2057343...22016913..265444281.8317272277
.48.2644.21752..390840..20539926..362503120.6509404451
.70.6118.70595.2166393.204332167.6317232175

Examples

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

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: [order 34] for n>37
Empirical for row n:
n=1: a(n) = a(n-2) +2*a(n-3)
n=2: [order 10] for n>12
n=3: [order 52] for n>59

A241435 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 one plus the sum of the elements antidiagonally to its northeast, modulo 4.

Original entry on oeis.org

2, 3, 3, 4, 5, 4, 7, 10, 2, 7, 10, 21, 22, 3, 10, 15, 45, 74, 97, 5, 15, 24, 88, 158, 515, 213, 6, 24, 35, 181, 448, 1563, 1527, 381, 9, 35, 54, 378, 1272, 5915, 7495, 5304, 1005, 10, 54, 83, 710, 3284, 22712, 45139, 37148, 20690, 1900, 15, 83, 124, 1460, 8331, 76145
Offset: 1

Views

Author

R. H. Hardin, Apr 22 2014

Keywords

Comments

Table starts
..2..3.....4......7.......10.........15..........24..........35..........54
..3..5....10.....21.......45.........88.........181.........378.........710
..4..2....22.....74......158........448........1272........3284........8331
..7..3....97....515.....1563.......5915.......22712.......76145......270960
.10..5...213...1527.....7495......45139......282527.....1304136.....6927135
.15..6...381...5304....37148.....377314.....4122537....29425635...269064197
.24..9..1005..20690...218885....4136727....79901137..1058201862.16609740868
.35.10..1900..61348..1059975...34541924..1231102996.34796682706
.54.15..4137.257119..7257895..418453966.26880310825
.83.21.10518.920918.44141371.4088141292

Examples

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

Crossrefs

Column and row 1 are A159288(n+1)

Formula

Empirical for column k:
k=1: a(n) = a(n-2) +2*a(n-3)
k=2: [order 11] for n>13
Empirical for row n:
n=1: a(n) = a(n-2) +2*a(n-3)
n=2: [order 22] for n>24

A239986 T(n,k)=Number of nXk 0..3 arrays with no element equal to zero plus the sum of elements to its left or two plus the sum of the elements above it or one plus the sum of the elements diagonally to its northwest, modulo 4.

Original entry on oeis.org

1, 1, 2, 1, 3, 3, 1, 4, 6, 4, 1, 5, 13, 16, 7, 1, 6, 22, 56, 40, 10, 1, 7, 38, 171, 261, 84, 15, 1, 8, 65, 530, 1391, 935, 208, 24, 1, 9, 107, 1495, 7113, 9079, 4113, 474, 35, 1, 10, 169, 4059, 31226, 83658, 70107, 16724, 1047, 54, 1, 11, 257, 10121, 131242, 652346
Offset: 1

Views

Author

R. H. Hardin, Mar 30 2014

Keywords

Comments

Table starts
..1....1......1........1..........1............1............1............1
..2....3......4........5..........6............7............8............9
..3....6.....13.......22.........38...........65..........107..........169
..4...16.....56......171........530.........1495.........4059........10121
..7...40....261.....1391.......7113........31226.......131242.......514539
.10...84....935.....9079......83658.......652346......4803152.....33097266
.15..208...4113....70107....1174822.....16721012....226886115...2823199343
.24..474..16724...514297...15307425....381369904...9004871354.198719581101
.35.1047..63746..3533132..192702130...9009351655.404795616742
.54.2530.275188.27478686.2733573580.233083355837

Examples

			Some solutions for n=4 k=4
..3..0..0..0....3..0..0..0....3..0..0..0....3..0..0..0....3..0..0..0
..3..1..3..0....2..3..0..3....3..1..3..0....2..1..0..0....2..1..0..0
..3..1..2..1....2..0..1..2....3..2..0..3....2..0..3..3....2..0..3..0
..2..1..0..0....3..0..0..1....2..3..0..3....3..2..2..2....2..0..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: a(n) = 2*a(n-2) +10*a(n-3) -a(n-4) -5*a(n-5) -15*a(n-6) +a(n-7) +4*a(n-8) +2*a(n-9) +10*a(n-10) +5*a(n-11) -6*a(n-13)
Empirical for row n:
n=1: a(n) = 1
n=2: a(n) = n + 1
n=3: a(n) = (1/24)*n^4 - (1/4)*n^3 + (71/24)*n^2 - (43/4)*n + 23 for n>3
n=4: [polynomial of degree 10] for n>12
n=5: [polynomial of degree 24] for n>31
n=6: [polynomial of degree 55] for n>73

A241356 T(n,k) = Number of n X k 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 one 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, 2, 3, 4, 3, 4, 6, 9, 3, 7, 8, 17, 19, 4, 10, 14, 23, 51, 55, 5, 15, 20, 53, 61, 128, 72, 5, 24, 30, 103, 230, 228, 248, 124, 7, 35, 48, 160, 641, 1721, 615, 624, 243, 8, 54, 70, 344, 960, 5663, 6307, 2062, 1323, 370, 9, 83, 108, 643, 3746, 11909, 32942, 35880, 6380, 2715
Offset: 1

Views

Author

R. H. Hardin, Apr 20 2014

Keywords

Comments

Table starts
..2..2...4.....6......8.......14........20.........30.........48.........70
..3..3...9....17.....23.......53.......103........160........344........643
..4..3..19....51.....61......230.......641........960.......3746.......9339
..7..4..55...128....228.....1721......5663......11909......69946.....220363
.10..5..72...248....615.....6307.....32942......81541.....704210....3476469
.15..5.124...624...2062....35880....247664.....921726...10840453...85630246
.24..7.243..1323...6380...183400...1904754...10693549..198803445.2384535274
.35..8.370..2715..17325...763750..12340892..109041097.3042023002
.54..9.695..5798..60671..4110488.104529676.1490516896
.83.12.956.11469.174659.18352240.729080777

Examples

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

Crossrefs

Column 1 is A159288(n+1).
Column 2 is A226503(n+8).
Row 1 is A239851.

Formula

Empirical for column k:
k=1: a(n) = a(n-2) +2*a(n-3).
k=2: a(n) = a(n-3) +a(n-5).
k=3: [order 68] for n > 85.
Empirical for row n:
n=1: a(n) = a(n-2) +2*a(n-3).
n=2: [order 17] for n > 20.

A240153 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 one 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, 5, 4, 7, 8, 11, 7, 10, 19, 20, 25, 10, 15, 36, 107, 67, 62, 15, 24, 57, 186, 676, 254, 144, 24, 35, 120, 450, 1328, 3993, 825, 329, 35, 54, 218, 1641, 5701, 11742, 22412, 2667, 775, 54, 83, 377, 2788, 24419, 88214, 108201, 131005, 8652, 1781, 83, 124, 758
Offset: 1

Views

Author

R. H. Hardin, Apr 02 2014

Keywords

Comments

Table starts
..2....3.....4........7.........10..........15..........24.........35
..3....5.....8.......19.........36..........57.........120........218
..4...11....20......107........186.........450........1641.......2788
..7...25....67......676.......1328........5701.......24419......52676
.10...62...254.....3993......11742.......88214......536744....1652584
.15..144...825....22412.....108201.....1608415....12812998...70360014
.24..329..2667...131005....1056699....30542203...417799464.3795213209
.35..775..8652...731518...10526838...584983851.14482686630
.54.1781.27929..4144347..107361960.11643589675
.83.4150.91436.23263202.1116331018

Examples

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

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 34] for n>36
Empirical for row n:
n=1: a(n) = a(n-2) +2*a(n-3)
n=2: [order 17] for n>19

A240192 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 three plus the sum of the elements diagonally to its northwest, modulo 4.

Original entry on oeis.org

1, 1, 2, 1, 5, 3, 1, 8, 12, 4, 1, 14, 37, 27, 7, 1, 26, 129, 138, 73, 10, 1, 50, 478, 771, 680, 154, 15, 1, 98, 1908, 5240, 7170, 2413, 358, 24, 1, 194, 7868, 40765, 91879, 44594, 10017, 872, 35, 1, 386, 32888, 336257, 1399773, 1005029, 333607, 43956, 1871, 54, 1
Offset: 1

Views

Author

R. H. Hardin, Apr 02 2014

Keywords

Comments

Table starts
..1....1......1.........1...........1............1.............1.............1
..2....5......8........14..........26...........50............98...........194
..3...12.....37.......129.........478.........1908..........7868.........32888
..4...27....138.......771........5240........40765........336257.......2843914
..7...73....680......7170.......91879......1399773......22849697.....385366572
.10..154...2413.....44594.....1005029.....28061567.....865984451...28244997476
.15..358..10017....333607....14022582....733907809...43398047802.2752449791995
.24..872..43956...2715035...206345434..19388521135.2070573220929
.35.1871.159668..17332017..2336659626.394134037392
.54.4438.681760.134735700.33576330306

Examples

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

Crossrefs

Column 1 is A159288
Row 2 is A164094(n-2)

Formula

Empirical for column k:
k=1: a(n) = a(n-2) +2*a(n-3)
k=2: [order 13]
Empirical for row n:
n=1: a(n) = a(n-1)
n=2: a(n) = 3*a(n-1) -2*a(n-2) for n>3
n=3: a(n) = 9*a(n-1) -27*a(n-2) +29*a(n-3) +6*a(n-4) -32*a(n-5) +16*a(n-6) for n>9
n=4: [order 29] for n>34

A241283 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 one 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, 4, 4, 3, 10, 7, 5, 9, 24, 10, 13, 41, 36, 56, 15, 17, 126, 236, 139, 132, 24, 35, 224, 773, 1615, 532, 312, 35, 90, 934, 1800, 6783, 12356, 2111, 736, 54, 141, 2741, 16843, 20717, 77955, 96171, 8473, 1736, 83, 288, 5225, 54167, 451318, 309657, 1009773
Offset: 1

Views

Author

R. H. Hardin, Apr 18 2014

Keywords

Comments

Table starts
....2......3........4..........7..........10............15...........24
....4......3........5.........13..........17............35...........90
...10......9.......41........126.........224...........934.........2741
...24.....36......236........773........1800.........16843........54167
...56....139.....1615.......6783.......20717........451318......1543713
..132....532....12356......77955......309657......15616828.....60486552
..312...2111....96171....1009773.....5423164.....730435588...2949336562
..736...8473...761754...14440961...113305157...40083129145.193899487190
.1736..34053..6079503..217830879..2759021846.2390612565177
.4096.136880.48655224.3381893022.75062814060

Examples

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

Crossrefs

Column 1 is A052912
Row 1 is A159288(n+1)

Formula

Empirical for column k:
k=1: a(n) = 2*a(n-1) +2*a(n-3)
k=2: [order 31]
Empirical for row n:
n=1: a(n)=a(n-2)+2*a(n-3)
n=2: [order 17] for n>18

A239599 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 one 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, 4, 3, 10, 3, 4, 24, 15, 4, 7, 56, 64, 31, 4, 10, 132, 244, 187, 82, 5, 15, 312, 1030, 1310, 643, 177, 7, 24, 736, 4303, 9806, 8773, 1737, 458, 8, 35, 1736, 17923, 76769, 128347, 38824, 7461, 1071, 11, 54, 4096, 75264, 611126, 1991329, 1031560, 282333, 24946
Offset: 1

Views

Author

R. H. Hardin, Mar 22 2014

Keywords

Comments

Table starts
..2..4....10.....24.......56........132.........312.........736........1736
..3..3....15.....64......244.......1030........4303.......17923.......75264
..4..4....31....187.....1310.......9806.......76769......611126.....4929897
..7..4....82....643.....8773.....128347.....1991329....31686730...510551001
.10..5...177...1737....38824....1031560....30460289...944810972.30050150163
.15..7...458...7461...282333...12509870...681399736.40483561185
.24..8..1071..24946..1583770..120511910.11135057785
.35.11..2150..78667..8002162.1104844380
.54.12..5209.313003.56967196
.83.16.11204.946740

Examples

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

Crossrefs

Column 1 is A159288(n+1)
Row 1 is A052912

Formula

Empirical for column k:
k=1: a(n) = a(n-2) +2*a(n-3)
k=2: a(n) = a(n-2) +a(n-5) for n>6
Empirical for row n:
n=1: a(n) = 2*a(n-1) +2*a(n-3)
n=2: [order 44] for n>47

A240271 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 one plus the sum of the elements diagonally to its northwest, modulo 4.

Original entry on oeis.org

2, 4, 3, 10, 7, 4, 24, 35, 14, 7, 56, 157, 118, 36, 10, 132, 713, 919, 582, 72, 15, 312, 3263, 7562, 8265, 2000, 170, 24, 736, 14895, 64721, 126286, 49921, 8353, 411, 35, 1736, 68101, 563496, 2059061, 1363144, 382690, 37422, 879, 54, 4096, 311509, 4956889
Offset: 1

Views

Author

R. H. Hardin, Apr 03 2014

Keywords

Comments

Table starts
..2....4......10.........24..........56..........132...........312
..3....7......35........157.........713.........3263.........14895
..4...14.....118........919........7562........64721........563496
..7...36.....582.......8265......126286......2059061......34514871
.10...72....2000......49921.....1363144.....40760821....1277623744
.15..170....8353.....382690....19210586...1063706501...63085436203
.24..411...37422....3076452...278945445..27923918285.3004792552569
.35..879..135463...19781372..3200032085.576407548906
.54.2106..580528..154994425.46095401280
.83.4874.2403439.1144262410

Examples

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

Crossrefs

Column 1 is A159288(n+1)
Row 1 is A052912

Formula

Empirical for column k:
k=1: a(n) = a(n-2) +2*a(n-3)
k=2: [order 13]
Empirical for row n:
n=1: a(n) = 2*a(n-1) +2*a(n-3)
n=2: [order 26] for n>28
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