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.

A239405 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, modulo 4.

Original entry on oeis.org

2, 4, 5, 8, 23, 12, 16, 105, 129, 28, 32, 478, 1337, 698, 66, 64, 2165, 13977, 16449, 3805, 156, 128, 9811, 144762, 394509, 205969, 20818, 368, 256, 44399, 1504399, 9340070, 11334364, 2590704, 113774, 868, 512, 201006, 15591122, 222457036, 614216271
Offset: 1

Views

Author

R. H. Hardin, Mar 17 2014

Keywords

Comments

Table starts
....2.......4..........8............16................32...................64
....5......23........105...........478..............2165.................9811
...12.....129.......1337.........13977............144762..............1504399
...28.....698......16449........394509...........9340070............222457036
...66....3805.....205969......11334364.........614216271..........33522573911
..156...20818....2590704.....326882784.......40566958960........5072216819342
..368..113774...32507376....9402398952.....2671846338458......765206237815409
..868..621754..408000104..270516990628...176044655676921...115478426410506313
.2048.3399032.5124790809.7789048968124.11610439554314901.17442858177037612521

Examples

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

Crossrefs

Column 1 is A239333
Row 1 is A000079

Formula

Empirical for column k:
k=1: a(n) = 2*a(n-1) +2*a(n-3)
k=2: [order 16]
k=3: [order 64]
Empirical for row n:
n=1: a(n) = 2*a(n-1)
n=2: a(n) = 3*a(n-1) +12*a(n-2) -18*a(n-3) -29*a(n-4) +19*a(n-5) +38*a(n-6) +8*a(n-7)
n=3: [order 25]
n=4: [order 91]

A240000 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 one plus the sum of the elements diagonally to its northwest, modulo 4.

Original entry on oeis.org

2, 3, 5, 4, 13, 12, 5, 25, 61, 28, 6, 42, 190, 256, 66, 7, 65, 526, 1372, 1117, 156, 8, 95, 1262, 6527, 10405, 5012, 368, 9, 133, 2766, 27415, 86360, 83029, 22592, 868, 10, 180, 5647, 104291, 635873, 1225281, 685898, 102336, 2048, 11, 237, 10878, 363859
Offset: 1

Views

Author

R. H. Hardin, Mar 30 2014

Keywords

Comments

Table starts
....2.......3.........4...........5............6............7............8
....5......13........25..........42...........65...........95..........133
...12......61.......190.........526.........1262.........2766.........5647
...28.....256......1372........6527........27415.......104291.......363859
...66....1117.....10405.......86360.......635873......4267171.....26152051
..156....5012.....83029.....1225281.....15981219....191691132...2090236137
..368...22592....685898....18392485....429788876...9314138750.182333502325
..868..102336...5825700...290513038..12392346376.491124025940
.2048..465662..50417154..4767970186.378942837634
.4832.2123857.441675344.80410934960

Examples

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

Crossrefs

Column 1 is A239333

Formula

Empirical for column k:
k=1: a(n) = 2*a(n-1) +2*a(n-3)
k=2: [order 26]
Empirical for row n:
n=1: a(n) = n + 1
n=2: a(n) = (1/6)*n^3 + 1*n^2 + (23/6)*n
n=3: [polynomial of degree 8] for n>6
n=4: [polynomial of degree 19] for n>20
n=5: [polynomial of degree 44] for n>52

A240460 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 one plus the sum of the elements diagonally to its northwest, modulo 4.

Original entry on oeis.org

2, 4, 5, 8, 21, 12, 16, 89, 102, 28, 32, 375, 874, 476, 66, 64, 1583, 7589, 8187, 2200, 156, 128, 6685, 65723, 143237, 75167, 10123, 368, 256, 28241, 568370, 2501883, 2632690, 682018, 46471, 868, 512, 119319, 4916340, 43654661, 92193017, 47636104, 6147372
Offset: 1

Views

Author

R. H. Hardin, Apr 05 2014

Keywords

Comments

Table starts
....2.......4..........8...........16............32.............64
....5......21.........89..........375..........1583...........6685
...12.....102........874.........7589.........65723.........568370
...28.....476.......8187.......143237.......2501883.......43654661
...66....2200......75167......2632690......92193017.....3228706651
..156...10123.....682018.....47636104....3337483054...234122685500
..368...46471....6147372....854671234..119643524281.16795323356869
..868..213000...55212526..15259447330.4265146133201
.2048..975380..494809053.271656519692
.4832.4464474.4428808128

Examples

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

Crossrefs

Column 1 is A239333
Row 1 is A000079

Formula

Empirical for column k:
k=1: a(n) = 2*a(n-1) +2*a(n-3)
k=2: [order 26]
Empirical for row n:
n=1: a(n) = 2*a(n-1)
n=2: a(n) = 6*a(n-1) -7*a(n-2) -4*a(n-3) +8*a(n-4)
n=3: [order 23]

A255115 Number of n-length words on {0,1,2} in which 0 appears only in runs of length 2.

Original entry on oeis.org

1, 2, 5, 12, 28, 66, 156, 368, 868, 2048, 4832, 11400, 26896, 63456, 149712, 353216, 833344, 1966112, 4638656, 10944000, 25820224, 60917760, 143723520, 339087488, 800010496, 1887468032, 4453111040, 10506243072, 24787422208, 58481066496, 137974619136
Offset: 0

Views

Author

Milan Janjic, Feb 14 2015

Keywords

Comments

Apparently a(n) = A239333(n).

Crossrefs

Programs

  • Mathematica
    RecurrenceTable[{a[0] == 1, a[1] == 2,  a[2]== 5, a[n] == 2 a[n - 1] + 2 a[n - 3]}, a[n], {n, 0, 29}]
  • PARI
    Vec(-(x^2+1)/(2*x^3+2*x-1) + O(x^100)) \\ Colin Barker, Feb 15 2015

Formula

a(n+3) = 2*a(n+2) + 2*a(n) with n>1, a(0) = 1, a(1) = 2, a(2)=5.
G.f.: -(x^2+1) / (2*x^3+2*x-1). - Colin Barker, Feb 15 2015
a(n) = A052912(n)+A052912(n-2). - R. J. Mathar, Jun 18 2015

A255116 Number of n-length words on {0,1,2,3} in which 0 appears only in runs of length 2.

Original entry on oeis.org

1, 3, 10, 33, 108, 354, 1161, 3807, 12483, 40932, 134217, 440100, 1443096, 4731939, 15516117, 50877639, 166828734, 547034553, 1793736576, 5881695930, 19286191449, 63239784075, 207364440015, 679951894392, 2229575035401, 7310818426248, 23972310961920
Offset: 0

Views

Author

Milan Janjic, Feb 14 2015

Keywords

Crossrefs

Programs

  • Mathematica
    RecurrenceTable[{a[0] == 1, a[1] == 3,  a[2]== 10, a[n] == 3 a[n - 1] + 3 a[n - 3]}, a[n], {n, 0, 25}]
    LinearRecurrence[{3,0,3},{1,3,10},30] (* Harvey P. Dale, Feb 20 2023 *)
  • PARI
    Vec(-(x^2+1)/(3*x^3+3*x-1) + O(x^100)) \\ Colin Barker, Feb 15 2015

Formula

a(n+3) = 3*a(n+2) + 3*a(n) with n>1, a(0) = 1, a(1) = 3, a(2) = 10.
G.f.: -(x^2+1) / (3*x^3+3*x-1). - Colin Barker, Feb 15 2015
a(n) = A089978(n) + A089978(n-2). - R. J. Mathar, Aug 04 2019

A255117 Number of n-length words on {0,1,2,3,4} in which 0 appears only in runs of length 2.

Original entry on oeis.org

1, 4, 17, 72, 304, 1284, 5424, 22912, 96784, 408832, 1726976, 7295040, 30815488, 130169856, 549859584, 2322700288, 9811480576, 41445360640, 175072243712, 739534897152, 3123921031168, 13195973099520, 55742031986688, 235463812071424, 994639140683776
Offset: 0

Views

Author

Milan Janjic, Feb 14 2015

Keywords

Crossrefs

Programs

  • Mathematica
    RecurrenceTable[{a[0] == 1, a[1] == 4,  a[2]== 17, a[n] == 4 a[n - 1] + 4 a[n - 3]}, a[n], {n, 0, 25}]
  • PARI
    Vec(-(x^2+1)/(4*x^3+4*x-1) + O(x^100)) \\ Colin Barker, Feb 15 2015

Formula

a(n+3) = 4*a(n+2) + 4*a(n) with n>1, a(0) = 1, a(1) = 4, a(2) = 17.
G.f.: -(x^2+1) / (4*x^3+4*x-1). - Colin Barker, Feb 15 2015
a(n) = A089979(n) + A089979(n-2). - R. J. Mathar, Aug 04 2019

A255118 Number of n-length words on {0,1,2,3,4,5} in which 0 appears only in runs of length 2.

Original entry on oeis.org

1, 5, 26, 135, 700, 3630, 18825, 97625, 506275, 2625500, 13615625, 70609500, 366175000, 1898953125, 9847813125, 51069940625, 264844468750, 1373461409375, 7122656750000, 36937506093750, 191554837515625, 993387471328125, 5151624887109375, 26715898623125000
Offset: 0

Views

Author

Milan Janjic, Feb 14 2015

Keywords

Crossrefs

Programs

  • Mathematica
    RecurrenceTable[{a[0] == 1, a[1] == 5,  a[2]== 26, a[n] == 5 a[n - 1] + 5 a[n - 3]}, a[n], {n, 0, 20}]
  • PARI
    Vec(-(x^2+1)/(5*x^3+5*x-1) + O(x^100)) \\ Colin Barker, Feb 15 2015

Formula

a(n+3) = 5*a(n+2) + 5*a(n) with n>1, a(0) = 1, a(1) = 5, a(2) = 26.
G.f.: -(x^2+1) / (5*x^3+5*x-1). - Colin Barker, Feb 15 2015

A255119 Number of n-length words on {0,1,2,3,4,5,6} in which 0 appears only in runs of length 2.

Original entry on oeis.org

1, 6, 37, 228, 1404, 8646, 53244, 327888, 2019204, 12434688, 76575456, 471567960, 2904015888, 17883548064, 110130696144, 678208272192, 4176550921536, 25720089706080, 158389787869632, 975398032747008, 6006708734718528, 36990591135528960
Offset: 0

Views

Author

Milan Janjic, Feb 14 2015

Keywords

Crossrefs

Programs

  • Mathematica
    RecurrenceTable[{a[0] == 1, a[1] == 6,  a[2]== 37, a[n] == 6 a[n - 1] + 6 a[n - 3]}, a[n], {n, 0, 20}]
    LinearRecurrence[{6,0,6},{1,6,37},30] (* Harvey P. Dale, Nov 06 2017 *)
  • PARI
    Vec(-(x^2+1)/(6*x^3+6*x-1) + O(x^100)) \\ Colin Barker, Feb 15 2015

Formula

a(n+3) = 6*a(n+2) + 6*a(n) with n>1, a(0) = 1, a(1) = 6, a(2) = 37.
G.f.: -(x^2+1) / (6*x^3+6*x-1). - Colin Barker, Feb 15 2015
Showing 1-8 of 8 results.