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.

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A220579 T(n,k)=Equals one maps: number of nXk binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal and antidiagonal neighbors in a random 0..1 nXk array.

Original entry on oeis.org

1, 2, 1, 4, 8, 1, 8, 21, 32, 1, 16, 115, 91, 128, 1, 32, 371, 1441, 375, 512, 1, 64, 1504, 8334, 17505, 1487, 2048, 1, 128, 5240, 64497, 165130, 205323, 5835, 8192, 1, 256, 19904, 436288, 2652007, 3162375, 2352642, 22775, 32768, 1, 512, 71787, 3036588
Offset: 1

Views

Author

R. H. Hardin Dec 16 2012

Keywords

Comments

Table starts
.1.......2.......4..........8..........16...........32...........64.........128
.1.......8......21........115.........371.........1504.........5240.......19904
.1......32......91.......1441........8334........64497.......436288.....3036588
.1.....128.....375......17505......165130......2652007.....33180533...450926562
.1.....512....1487.....205323.....3162375....106841503...2449921734.65126683335
.1....2048....5835....2352642....59690533...4239598056.178051989526
.1....8192...22775...26616961..1120269376.166807007000
.1...32768...88683..299065708.20961430054
.1..131072..344975.3347252663
.1..524288.1341395
.1.2097152
.1

Examples

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

Crossrefs

Column 2 is A004171(n-1)
Row 1 is A000079(n-1)

A301841 T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 1 or 2 horizontally or antidiagonally adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 2, 2, 4, 8, 4, 8, 25, 32, 8, 16, 81, 139, 128, 16, 32, 263, 678, 773, 512, 32, 64, 855, 3182, 5748, 4299, 2048, 64, 128, 2778, 15199, 39703, 48802, 23909, 8192, 128, 256, 9027, 72514, 281758, 496085, 414385, 132971, 32768, 256, 512, 29333, 346244
Offset: 1

Views

Author

R. H. Hardin, Mar 27 2018

Keywords

Comments

Table starts
...1......2.......4.........8..........16...........32.............64
...2......8......25........81.........263..........855...........2778
...4.....32.....139.......678........3182........15199..........72514
...8....128.....773......5748.......39703.......281758........1986213
..16....512....4299.....48802......496085......5240684.......54948498
..32...2048...23909....414385.....6196305.....97439921.....1518341751
..64...8192..132971...3518619....77396422...1812097252....41966406867
.128..32768..739525..29877293...966770632..33701001773..1159968653556
.256.131072.4112907.253694309.12076215811.626769301255.32062561937804

Examples

			Some solutions for n=5 k=4
..0..1..1..0. .0..1..0..1. .0..1..1..1. .0..0..0..0. .0..0..1..1
..1..0..1..0. .1..1..0..1. .1..0..1..0. .1..1..0..1. .0..1..0..1
..1..0..1..1. .1..0..1..0. .1..0..1..1. .0..1..0..1. .1..1..0..1
..0..1..0..0. .0..0..1..0. .1..0..1..1. .0..0..1..0. .0..1..0..0
..1..0..1..0. .0..1..0..1. .1..0..0..0. .1..1..0..1. .1..1..1..1
		

Crossrefs

Column 1 is A000079(n-1).
Column 2 is A004171(n-1).
Row 1 is A000079(n-1).

Formula

Empirical for column k:
k=1: a(n) = 2*a(n-1)
k=2: a(n) = 4*a(n-1)
k=3: a(n) = 7*a(n-1) -8*a(n-2) for n>3
k=4: a(n) = 13*a(n-1) -46*a(n-2) +72*a(n-3) -57*a(n-4) +16*a(n-5) for n>6
k=5: [order 11] for n>13
k=6: [order 25] for n>27
k=7: [order 53] for n>56
Empirical for row n:
n=1: a(n) = 2*a(n-1)
n=2: a(n) = 3*a(n-1) +a(n-2) -2*a(n-4) for n>6
n=3: [order 12] for n>14
n=4: [order 35] for n>38
n=5: [order 99] for n>104

A302265 T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 1, 2 or 3 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 2, 2, 4, 8, 4, 8, 29, 32, 8, 16, 105, 153, 128, 16, 32, 384, 772, 818, 512, 32, 64, 1405, 3818, 5922, 4386, 2048, 64, 128, 5135, 19191, 40296, 45717, 23516, 8192, 128, 256, 18766, 96004, 284428, 429854, 353229, 126162, 32768, 256, 512, 68589, 481261
Offset: 1

Views

Author

R. H. Hardin, Apr 04 2018

Keywords

Comments

Table starts
...1......2.......4.........8.........16...........32............64
...2......8......29.......105........384.........1405..........5135
...4.....32.....153.......772.......3818........19191.........96004
...8....128.....818......5922......40296.......284428.......1984001
..16....512....4386.....45717.....429854......4289139......41994750
..32...2048...23516....353229....4608075.....64975832.....893462062
..64...8192..126162...2727755...49315068....982041385...18964765818
.128..32768..676988..21069318..527911860..14850510984..402597400706
.256.131072.3632880.162753849.5651844495.224584502616.8547940665506

Examples

			Some solutions for n=5 k=4
..0..0..1..1. .0..1..0..1. .0..1..0..1. .0..0..0..0. .0..1..1..0
..0..1..1..0. .0..1..1..0. .0..1..0..0. .0..1..1..0. .1..0..1..1
..1..1..0..0. .0..0..1..0. .0..1..0..0. .0..1..0..1. .1..1..0..0
..0..1..1..1. .1..1..0..1. .0..1..0..0. .0..1..0..1. .0..1..0..1
..1..0..0..0. .0..0..0..1. .0..1..1..1. .0..0..1..0. .1..1..0..0
		

Crossrefs

Column 1 is A000079(n-1).
Column 2 is A004171(n-1).
Row 1 is A000079(n-1).

Formula

Empirical for column k:
k=1: a(n) = 2*a(n-1)
k=2: a(n) = 4*a(n-1)
k=3: a(n) = 6*a(n-1) -2*a(n-2) +2*a(n-3) -54*a(n-4) +16*a(n-5) for n>6
k=4: [order 17] for n>18
k=5: [order 70] for n>71
Empirical for row n:
n=1: a(n) = 2*a(n-1)
n=2: a(n) = 3*a(n-1) +a(n-2) +4*a(n-3) +4*a(n-4)
n=3: [order 12] for n>13
n=4: [order 44] for n>45

A013776 a(n) = 2^(4*n+1).

Original entry on oeis.org

2, 32, 512, 8192, 131072, 2097152, 33554432, 536870912, 8589934592, 137438953472, 2199023255552, 35184372088832, 562949953421312, 9007199254740992, 144115188075855872, 2305843009213693952
Offset: 0

Views

Author

Keywords

Comments

a(n) ~ -Pi*E(2*n)/B(2*n), E(n) Euler number, B(n) Bernoulli number. - Peter Luschny, Oct 28 2012
Equivalently, powers of 2 with final digit 2. - Muniru A Asiru, Mar 15 2019
As phi(a(n)) = (2^n)^4 is a perfect biquadrate (where phi is the Euler totient A000010), this is a subsequence of A078164 and A307690. - Bernard Schott, Mar 28 2022

Examples

			G.f. = 2 + 32*x + 512*x^2 + 8192*x^3 + 131072*x^4 + 2097152*x^5 + ...
		

Crossrefs

Subsequence of A307690.
Intersection of A000079 and A078164.

Programs

Formula

From Philippe Deléham, Nov 23 2008: (Start)
a(n) = 16*a(n-1), n > 0, a(0) = 2.
G.f.: 2/(1 - 16*x). (End)
From Peter Bala, Nov 29 2015: (Start)
a(n) = Sum_{k = 0..n} binomial(2*k,k)*binomial(4*n + 2 - 2*k, 2*n + 1 - k).
Bisection of A264960. (End)
a(n) = A000079(A016813(n)). - Michel Marcus, Nov 30 2015
a(n) = Sum_{k = 0..2*n} binomial(4*n + 2, 2*k + 1) = A004171(2*n). - Peter Bala, Nov 25 2016
E.g.f.: 2*exp(16*x). - G. C. Greubel, Jun 30 2019
From Bernard Schott, Apr 15 2022: (Start)
Sum_{n>=0} 1/a(n) = 8/15.
Sum_{n>=0} (-1)^n/a(n) = 8/17. (End)

Extensions

Wrong comment deleted by Kevin Ryde, Apr 16 2022

A028403 Number of types of Boolean functions of n variables under a certain group.

Original entry on oeis.org

4, 12, 40, 144, 544, 2112, 8320, 33024, 131584, 525312, 2099200, 8392704, 33562624, 134234112, 536903680, 2147549184, 8590065664, 34360000512, 137439477760, 549756862464, 2199025352704, 8796097216512, 35184380477440, 140737505132544, 562949986975744
Offset: 1

Views

Author

Keywords

Crossrefs

This sequence in base 2 is A163450. - Jaroslav Krizek, Jul 27 2009

Programs

  • Magma
    [2^(2*n-1) +2^n: n in [1..30]]; // G. C. Greubel, Jul 07 2021
    
  • Mathematica
    Join[{4},Table[FromDigits[Join[{1},PadRight[{},n-2,0],{1},PadRight[ {},n,0]],2],{n,2,30}]] (* Harvey P. Dale, Jan 24 2021 *)
  • PARI
    Vec(4*x*(1-3*x)/((1-2*x)*(1-4*x)) + O(x^100)) \\ Colin Barker, Sep 30 2014
    
  • Sage
    [2^(2*n-1) +2^n for n in (1..30)] # G. C. Greubel, Jul 07 2021

Formula

a(n) = (2^(n-1) + 1)*2^n = 2*A007582(n-1). - Ralf Stephan, Mar 24 2004
a(n) = A000079(n) * (A000079(n-1) + 1) = (A000051(n) - 1) * A000051(n-1) = A000079(n) * A000051(n-1) = (A000051(n) - 1) * (A000079(n-1) + 1) = 2^n * (2^(n-1) + 1). a(n+1) = A000079(n+1) * (A000079(n) + 1) = (A000051(n+1) - 1) * A000051(n) = A000079(n+1) * A000051(n) = (A000051(n+1) - 1) * (A000079(n) + 1) = 2^(n+1) * (2^n + 1). a(n) = A081294(n) + A000079(n) = A004171(n-1) + A000079(n) = 2^(2n-1) + 2^n. - Jaroslav Krizek, Jul 27 2009
From Colin Barker, Sep 30 2014: (Start)
a(n) = 6*a(n-1) - 8*a(n-2).
G.f.: 4*x*(1 - 3*x)/((1-2*x)*(1-4*x)). (End)
E.g.f.: (1/2)*(exp(2*x) -1)*(exp(2*x) + 3). - G. C. Greubel, Jul 07 2021

Extensions

More terms from Vladeta Jovovic, Feb 24 2000
More terms from Colin Barker, Sep 30 2014

A208709 T(n,k)=Number of nXk 0..1 arrays with new values 0..1 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.

Original entry on oeis.org

1, 2, 2, 4, 8, 4, 8, 28, 32, 8, 16, 100, 196, 128, 16, 32, 356, 1268, 1372, 512, 32, 64, 1268, 8128, 16084, 9604, 2048, 64, 128, 4516, 52184, 185344, 204020, 67228, 8192, 128, 256, 16084, 334948, 2142580, 4226368, 2587924, 470596, 32768, 256, 512, 57284, 2149988
Offset: 1

Views

Author

R. H. Hardin Mar 01 2012

Keywords

Comments

Table starts
...1.....2.......4.........8..........16............32..............64
...2.....8......28.......100.........356..........1268............4516
...4....32.....196......1268........8128.........52184..........334948
...8...128....1372.....16084......185344.......2142580........24754628
..16...512....9604....204020.....4226368......87985748......1830045552
..32..2048...67228...2587924....96373248....3613193828....135288700496
..64..8192..470596..32826932..2197585152..148378294612..10001404535216
.128.32768.3294172.416398420.50111214592.6093257064980.739367693888784

Examples

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

Crossrefs

Column 2 is A004171(n-1)
Row 2 is A104934

A302069 T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 1, 2 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 2, 2, 4, 8, 4, 8, 25, 32, 8, 16, 81, 148, 128, 16, 32, 263, 748, 884, 512, 32, 64, 855, 3657, 7070, 5296, 2048, 64, 128, 2778, 18108, 54177, 67070, 31760, 8192, 128, 256, 9027, 89658, 420121, 807601, 636852, 190528, 32768, 256, 512, 29333, 444359
Offset: 1

Views

Author

R. H. Hardin, Mar 31 2018

Keywords

Comments

Table starts
...1......2.......4.........8..........16............32..............64
...2......8......25........81.........263...........855............2778
...4.....32.....148.......748........3657.........18108...........89658
...8....128.....884......7070.......54177........420121.........3247765
..16....512....5296.....67070......807601.......9825815.......119508742
..32...2048...31760....636852....12063625.....230634314......4418931065
..64...8192..190528...6048836...180330117....5420105343....163660519064
.128..32768.1143104..57457232..2696254757..127431664603...6065045335103
.256.131072.6858496.545796112.40316943551.2996509042607.224815724811979

Examples

			Some solutions for n=5 k=4
..0..1..0..0. .0..1..0..0. .0..0..1..1. .0..1..1..0. .0..1..0..0
..1..0..0..0. .1..1..1..0. .0..1..0..0. .1..0..1..0. .0..1..1..1
..1..0..1..0. .0..1..1..0. .0..0..1..0. .0..1..0..1. .1..0..1..0
..1..1..1..0. .0..0..1..0. .1..1..1..0. .1..0..1..0. .0..0..1..0
..1..1..0..1. .1..0..1..1. .1..1..0..1. .0..0..0..1. .0..0..1..0
		

Crossrefs

Column 1 is A000079(n-1).
Column 2 is A004171(n-1).
Row 1 is A000079(n-1).
Row 2 is A301842.

Formula

Empirical for column k:
k=1: a(n) = 2*a(n-1)
k=2: a(n) = 4*a(n-1)
k=3: a(n) = 8*a(n-1) -12*a(n-2) for n>3
k=4: a(n) = 16*a(n-1) -76*a(n-2) +148*a(n-3) -124*a(n-4) +36*a(n-5) for n>6
k=5: [order 11] for n>13
k=6: [order 25] for n>27
k=7: [order 53] for n>56
Empirical for row n:
n=1: a(n) = 2*a(n-1)
n=2: a(n) = 3*a(n-1) +a(n-2) -2*a(n-4) for n>6
n=3: [order 15] for n>18
n=4: [order 53] for n>58

A302741 T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 1, 2, 3 or 4 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 2, 2, 4, 8, 4, 8, 32, 32, 8, 16, 128, 228, 128, 16, 32, 512, 1637, 1652, 512, 32, 64, 2048, 11814, 21625, 11980, 2048, 64, 128, 8192, 85268, 285613, 286631, 86916, 8192, 128, 256, 32768, 615589, 3778433, 6947036, 3798398, 630604, 32768, 256, 512, 131072
Offset: 1

Views

Author

R. H. Hardin, Apr 12 2018

Keywords

Comments

Table starts
...1......2........4..........8............16..............32
...2......8.......32........128...........512............2048
...4.....32......228.......1637.........11814...........85268
...8....128.....1652......21625........285613.........3778433
..16....512....11980.....286631.......6947036.......168799572
..32...2048....86916....3798398.....168833401......7530280825
..64...8192...630604...50347423....4104946296....336148647504
.128..32768..4575332..667361051...99807877377..15005851329729
.256.131072.33196332.8845980434.2426739457531.669868217032865

Examples

			Some solutions for n=5 k=4
..0..0..1..0. .0..0..1..0. .0..0..1..0. .0..0..0..1. .0..0..1..0
..0..0..0..0. .0..0..1..0. .0..0..0..0. .0..1..0..1. .0..1..0..1
..0..1..1..1. .0..1..1..0. .0..1..1..1. .0..1..0..0. .0..0..1..0
..1..0..0..0. .1..1..0..1. .0..0..1..0. .1..1..0..0. .1..1..1..1
..0..0..1..0. .1..1..0..1. .0..0..1..1. .0..1..1..1. .1..1..0..0
		

Crossrefs

Column 1 is A000079(n-1).
Column 2 is A004171(n-1).
Row 1 is A000079(n-1).
Row 2 is A004171(n-1).

Formula

Empirical for column k:
k=1: a(n) = 2*a(n-1)
k=2: a(n) = 4*a(n-1)
k=3: a(n) = 7*a(n-1) +2*a(n-2) +2*a(n-3) -20*a(n-4) -16*a(n-5)
k=4: [order 15]
k=5: [order 46]
Empirical for row n:
n=1: a(n) = 2*a(n-1)
n=2: a(n) = 4*a(n-1)
n=3: a(n) = 7*a(n-1) +4*a(n-2) -17*a(n-3) -3*a(n-4) -9*a(n-6) +14*a(n-7) for n>8
n=4: [order 15] for n>16
n=5: [order 64] for n>65

A302808 T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 1, 2, 3 or 5 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 2, 2, 4, 8, 4, 8, 29, 32, 8, 16, 105, 169, 128, 16, 32, 384, 934, 1010, 512, 32, 64, 1405, 5117, 8718, 6084, 2048, 64, 128, 5135, 28128, 74072, 82367, 36456, 8192, 128, 256, 18766, 154494, 632004, 1089773, 773520, 218640, 32768, 256, 512, 68589, 848519
Offset: 1

Views

Author

R. H. Hardin, Apr 13 2018

Keywords

Comments

Table starts
...1......2.......4.........8..........16............32..............64
...2......8......29.......105.........384..........1405............5135
...4.....32.....169.......934........5117.........28128..........154494
...8....128....1010......8718.......74072........632004.........5396562
..16....512....6084.....82367.....1089773......14458177.......192211013
..32...2048...36456....773520....15904814.....327603711......6769884156
..64...8192..218640...7267160...232260380....7428713676....238687785290
.128..32768.1312416..68346451..3396923500..168777255305...8434497360938
.256.131072.7873344.642498696.49653502029.3832039683236.297820640670676

Examples

			Some solutions for n=5 k=4
..0..1..0..0. .0..0..0..0. .0..0..1..0. .0..0..1..0. .0..1..1..0
..1..0..1..1. .0..1..1..0. .1..0..1..0. .0..0..1..1. .1..1..1..1
..1..0..1..0. .0..1..0..1. .1..0..1..1. .0..0..1..1. .0..0..0..0
..0..1..0..1. .0..0..0..0. .1..0..0..0. .1..0..1..1. .0..1..1..0
..1..1..0..0. .0..0..1..1. .1..0..1..0. .1..0..1..0. .1..1..1..1
		

Crossrefs

Column 1 is A000079(n-1).
Column 2 is A004171(n-1).
Row 1 is A000079(n-1).
Row 2 is A302266.

Formula

Empirical for column k:
k=1: a(n) = 2*a(n-1)
k=2: a(n) = 4*a(n-1)
k=3: a(n) = 6*a(n-1) +24*a(n-3) -144*a(n-4) for n>6
k=4: [order 18] for n>20
k=5: [order 90] for n>92
Empirical for row n:
n=1: a(n) = 2*a(n-1)
n=2: a(n) = 3*a(n-1) +a(n-2) +4*a(n-3) +4*a(n-4)
n=3: [order 13] for n>15
n=4: [order 48] for n>50

A302965 T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 1, 2, 3 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

Original entry on oeis.org

1, 2, 2, 4, 8, 4, 8, 29, 32, 8, 16, 105, 154, 128, 16, 32, 384, 786, 833, 512, 32, 64, 1405, 3924, 6206, 4527, 2048, 64, 128, 5135, 19868, 43588, 49521, 24602, 8192, 128, 256, 18766, 100161, 314989, 493132, 395493, 133757, 32768, 256, 512, 68589, 505908
Offset: 1

Views

Author

R. H. Hardin, Apr 16 2018

Keywords

Comments

Table starts
...1......2.......4.........8.........16...........32.............64
...2......8......29.......105........384.........1405...........5135
...4.....32.....154.......786.......3924........19868.........100161
...8....128.....833......6206......43588.......314989........2257439
..16....512....4527.....49521.....493132......5122000.......52646395
..32...2048...24602....395493....5602382.....83644490.....1233435694
..64...8192..133757...3157171...63612987...1365216668....28906043997
.128..32768..727293..25208524..722646394..22301032112...677939939546
.256.131072.3954552.201291251.8212135689.364489574945.15913688413086

Examples

			Some solutions for n=5 k=4
..0..1..0..1. .0..1..1..0. .0..0..0..1. .0..0..1..0. .0..0..1..0
..1..1..0..0. .0..0..0..0. .0..0..1..1. .1..0..1..1. .1..0..1..0
..0..1..0..0. .1..1..1..1. .1..0..1..1. .0..1..0..0. .1..0..1..0
..1..1..1..1. .1..0..0..1. .1..0..1..0. .0..1..0..0. .1..0..1..1
..1..0..0..0. .1..0..1..0. .1..0..1..0. .0..1..0..1. .0..1..0..0
		

Crossrefs

Column 1 is A000079(n-1).
Column 2 is A004171(n-1).
Row 1 is A000079(n-1).
Row 2 is A302266.

Formula

Empirical for column k:
k=1: a(n) = 2*a(n-1)
k=2: a(n) = 4*a(n-1)
k=3: a(n) = 7*a(n-1) -7*a(n-2) -56*a(n-4) +64*a(n-5) for n>6
k=4: [order 19] for n>20
k=5: [order 80] for n>81
Empirical for row n:
n=1: a(n) = 2*a(n-1)
n=2: a(n) = 3*a(n-1) +a(n-2) +4*a(n-3) +4*a(n-4)
n=3: [order 12] for n>13
n=4: [order 44] for n>45
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