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 1-5 of 5 results.

A196856 T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 3,1,0,2,4 for x=0,1,2,3,4.

Original entry on oeis.org

1, 2, 2, 4, 11, 4, 6, 38, 38, 6, 12, 136, 206, 136, 12, 22, 496, 1370, 1370, 496, 22, 40, 1792, 8767, 16876, 8767, 1792, 40, 74, 6440, 56470, 199125, 199125, 56470, 6440, 74, 136, 23306, 363685, 2369631, 4326720, 2369631, 363685, 23306, 136, 250, 84180
Offset: 1

Views

Author

R. H. Hardin Oct 06 2011

Keywords

Comments

Every 0 is next to 0 3's, every 1 is next to 1 1's, every 2 is next to 2 0's, every 3 is next to 3 2's, every 4 is next to 4 4's
Table starts
...1......2........4...........6.............12...............22
...2.....11.......38.........136............496.............1792
...4.....38......206........1370...........8767............56470
...6....136.....1370.......16876.........199125..........2369631
..12....496.....8767......199125........4326720.........94652804
..22...1792....56470.....2369631.......94652804.......3805929995
..40...6440...363685....28194191.....2069281146.....152929723254
..74..23306..2343584...335586650....45250654402....6148984299163
.136..84180.15108610..3993458371...989582452566..247223213832440
.250.303664.97376923.47516896629.21641093339471.9939022894905148

Examples

			Some solutions for n=6 k=4
..0..0..0..2....0..0..0..0....0..0..0..0....0..0..0..2....0..0..0..1
..0..0..0..0....0..0..1..2....0..0..2..2....0..0..0..0....0..0..0..1
..1..1..2..0....2..2..1..0....1..1..2..0....0..0..1..1....2..1..1..0
..0..0..2..2....0..0..2..2....0..0..0..0....0..1..0..0....0..0..2..0
..2..2..0..0....1..1..0..0....0..0..1..2....2..1..0..0....0..0..1..1
..0..2..0..0....0..0..0..0....0..2..1..0....0..0..0..2....0..0..2..0
		

Crossrefs

Column 1 is A196700

A196950 T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 4,1,0,2,3 for x=0,1,2,3,4.

Original entry on oeis.org

1, 2, 2, 4, 11, 4, 6, 38, 38, 6, 12, 136, 210, 136, 12, 22, 496, 1416, 1416, 496, 22, 40, 1792, 9199, 18060, 9199, 1792, 40, 74, 6440, 60206, 220433, 220433, 60206, 6440, 74, 136, 23306, 393585, 2711711, 5039158, 2711711, 393585, 23306, 136, 250, 84180
Offset: 1

Views

Author

R. H. Hardin Oct 08 2011

Keywords

Comments

Every 0 is next to 0 4's, every 1 is next to 1 1's, every 2 is next to 2 0's, every 3 is next to 3 2's, every 4 is next to 4 3's
Table starts
...1......2.........4...........6.............12................22
...2.....11........38.........136............496..............1792
...4.....38.......210........1416...........9199.............60206
...6....136......1416.......18060.........220433...........2711711
..12....496......9199......220433........5039158.........115982718
..22...1792.....60206.....2711711......115982718........4998342821
..40...6440....393585....33344883.....2668162530......215125975535
..74..23306...2575161...410312728....61397041229.....9264434681345
.136..84180..16853437..5047886243..1412800280934...398999272140802
.250.303664.110272832.62090427845.32510004942226.17183027304906341

Examples

			Some solutions for n=6 k=4
..0..0..0..0....0..0..0..2....0..0..0..0....0..0..0..0....0..0..0..0
..0..0..0..0....0..0..0..0....0..0..0..0....0..0..1..0....0..0..0..2
..2..0..0..0....1..2..1..1....0..1..1..0....1..0..1..0....2..0..0..1
..2..0..1..2....1..0..0..2....1..0..0..0....1..2..0..0....1..2..2..1
..0..0..1..0....0..0..0..0....1..2..1..0....0..1..0..0....1..0..0..2
..1..1..0..0....0..2..2..0....0..0..1..0....0..1..2..0....0..0..0..0
		

Crossrefs

Column 1 is A196700
Column 2 is A196850

A242239 T(n,k)=Number of length n+k+1 0..k arrays with every value 0..k appearing at least once in every consecutive k+2 elements, and new values 0..k introduced in order.

Original entry on oeis.org

3, 6, 5, 10, 12, 8, 15, 22, 22, 13, 21, 35, 43, 40, 21, 28, 51, 71, 82, 74, 34, 36, 70, 106, 139, 157, 136, 55, 45, 92, 148, 211, 271, 304, 250, 89, 55, 117, 197, 298, 416, 531, 586, 460, 144, 66, 145, 253, 400, 592, 821, 1047, 1129, 846, 233, 78, 176, 316, 517, 799
Offset: 1

Views

Author

R. H. Hardin, May 08 2014

Keywords

Comments

Table starts
...3....6...10...15....21....28....36....45....55....66....78....91...105
...5...12...22...35....51....70....92...117...145...176...210...247...287
...8...22...43...71...106...148...197...253...316...386...463...547...638
..13...40...82..139...211...298...400...517...649...796...958..1135..1327
..21...74..157..271...416...592...799..1037..1306..1606..1937..2299..2692
..34..136..304..531...821..1174..1590..2069..2611..3216..3884..4615..5409
..55..250..586.1047..1626..2332..3165..4125..5212..6426..7767..9235.10830
..89..460.1129.2059..3231..4642..6308..8229.10405.12836.15522.18463.21659
.144..846.2176.4047..6411..9256.12587.16429.20782.25646.31021.36907.43304
.233.1556.4195.7955.12716.18442.25138.32821.41527.51256.62008.73783.86581

Examples

			Some solutions for n=5 k=4
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..1....1....1....1....1....1....1....1....1....1....1....1....1....0....1....1
..2....2....0....2....2....1....0....0....2....0....2....2....0....1....2....0
..1....3....2....3....3....2....2....2....3....2....3....3....2....2....3....2
..3....4....3....4....4....3....3....3....0....3....0....0....3....3....4....3
..4....0....4....1....0....4....4....4....4....4....4....4....4....4....1....4
..0....2....2....0....1....0....2....0....2....1....2....1....0....2....0....1
..2....1....1....0....2....1....1....1....1....0....1....2....1....0....2....0
..2....3....0....2....3....0....0....1....0....0....3....4....2....1....3....4
..1....0....0....3....0....2....2....2....3....2....2....3....3....1....0....2
		

Crossrefs

Column 1 is A000045(n+3)
Column 2 is A196700(n+3)
Row 1 is A000217(n+1)
Row 2 is A000326(n+1)
Row 3 is A069099(n+1)
Row 4 is A220083

Formula

Empirical for column k:
k=1: a(n) = a(n-1) +a(n-2)
k=2: a(n) = a(n-1) +a(n-2) +a(n-3)
k=3: a(n) = a(n-1) +a(n-2) +a(n-3) +a(n-4)
k=4: a(n) = a(n-1) +a(n-2) +a(n-3) +a(n-4) +a(n-5)
k=5: a(n) = a(n-1) +a(n-2) +a(n-3) +a(n-4) +a(n-5) +a(n-6)
k=6: a(n) = a(n-1) +a(n-2) +a(n-3) +a(n-4) +a(n-5) +a(n-6) +a(n-7)
k=7: a(n) = a(n-1) +a(n-2) +a(n-3) +a(n-4) +a(n-5) +a(n-6) +a(n-7) +a(n-8)
k=8: a(n) = a(n-1) +a(n-2) +a(n-3) +a(n-4) +a(n-5) +a(n-6) +a(n-7) +a(n-8) +a(n-9)
k=9: a(n) = a(n-1) +a(n-2) +a(n-3) +a(n-4) +a(n-5) +a(n-6) +a(n-7) +a(n-8) +a(n-9) +a(n-10)
Empirical for row n:
n=1: a(n) = (1/2)*n^2 + (3/2)*n + 1
n=2: a(n) = (3/2)*n^2 + (5/2)*n + 1
n=3: a(n) = (7/2)*n^2 + (7/2)*n + 1
n=4: a(n) = (15/2)*n^2 + (9/2)*n + 1
n=5: a(n) = (31/2)*n^2 + (11/2)*n + 1 for n>1
n=6: a(n) = (63/2)*n^2 + (13/2)*n + 1 for n>2
n=7: a(n) = (127/2)*n^2 + (15/2)*n + 1 for n>3
n=8: a(n) = (255/2)*n^2 + (17/2)*n + 1 for n>4
n=9: a(n) = (511/2)*n^2 + (19/2)*n + 1 for n>5
n=10: a(n) = (1023/2)*n^2 + (21/2)*n + 1 for n>6
n=11: a(n) = (2047/2)*n^2 + (23/2)*n + 1 for n>7
n=12: a(n) = (4095/2)*n^2 + (25/2)*n + 1 for n>8
n=13: a(n) = (8191/2)*n^2 + (27/2)*n + 1 for n>9
n=14: a(n) = (16383/2)*n^2 + (29/2)*n + 1 for n>10
n=15: a(n) = (32767/2)*n^2 + (31/2)*n + 1 for n>11
Empirical large-k generalization, for k>n-4: T(n,k) = ((2^n-1)/2)*k^2 + ((2*n+1)/2)*k + 1
Empirical recurrence generalization, for column k: a(n) = sum {i in 1..k+1} a(n-i)

A197001 Decimal expansion of the slope of the line y=mx which meets the curve y=1+cos(x) orthogonally over the interval [0, 2*Pi] (as in A197000).

Original entry on oeis.org

1, 0, 5, 4, 1, 7, 8, 4, 4, 2, 6, 5, 6, 8, 4, 2, 1, 7, 5, 1, 5, 7, 4, 7, 7, 3, 4, 3, 0, 5, 6, 7, 3, 4, 8, 3, 7, 4, 6, 1, 4, 2, 1, 0, 4, 5, 8, 9, 1, 6, 0, 6, 6, 4, 5, 3, 6, 7, 7, 2, 1, 8, 5, 0, 7, 8, 2, 3, 8, 0, 7, 2, 5, 6, 7, 6, 3, 2, 7, 7, 7, 9, 0, 9, 4, 3, 3, 8, 4, 5, 0, 3, 2, 0, 5, 7, 5, 4, 6, 9, 3
Offset: 1

Views

Author

Clark Kimberling, Oct 09 2011

Keywords

Comments

See the Mathematica program for a graph.
xo=1.2488014367215508560475125020128381535587614...
yo=1.3164595537507515212878992732671186100622603...
m=1.05417844265684217515747734305673483746142104...
|OP|=1.81454423617045980814297669595599066552030...

Crossrefs

Programs

  • Mathematica
    c = 1;
    xo = x /.
      FindRoot[x == Sin[x] (c + Cos[x]), {x, 1, 1.3}, WorkingPrecision -> 100]
    RealDigits[xo] (* A197000 *)
    m = 1/Sin[xo]
    RealDigits[m]  (* A197001 *)
    yo = m*xo
    d = Sqrt[xo^2 + yo^2]
    Show[Plot[{c + Cos[c*x], yo - (1/m) (x - xo)}, {x, 0, Pi}],  ContourPlot[{y == m*x}, {x, 0, Pi}, {y, 0, 2}], PlotRange -> All, AspectRatio -> Automatic, AxesOrigin -> Automatic]

A248959 Number of ternary words of length n in which all digits 0..2 occur in every subword of 4 consecutive digits.

Original entry on oeis.org

1, 3, 9, 27, 36, 72, 132, 240, 444, 816, 1500, 2760, 5076, 9336, 17172, 31584, 58092, 106848, 196524, 361464, 664836, 1222824, 2249124, 4136784, 7608732, 13994640, 25740156, 47343528, 87078324, 160162008, 294583860, 541824192, 996570060, 1832978112
Offset: 0

Views

Author

Andrew Woods, Jan 12 2015

Keywords

Comments

For n < 4 the constraint is voidly satisfied: each of the n-digit words satisfies the definition since there is no subword of length 4. - M. F. Hasler, Jan 13 2015

Crossrefs

Programs

  • Mathematica
    Join[{1,3,9,27},LinearRecurrence[{1,1,1},{36,72,132},30]] (* Harvey P. Dale, Mar 12 2015 *)
  • PARI
    Vec((1+2*x+5*x^2+14*x^3-3*x^4-3*x^6)/(1-x-x^2-x^3) + O(x^100)) \\ Colin Barker, Jan 12 2015; extended to indices 0..3 by M. F. Hasler, Jan 13 2015

Formula

G.f.: (1 + 2*x + 5*x^2 + 14*x^3 - 3*x^4 - 3*x^6)/(1 - x - x^2 - x^3). - Corrected by Colin Barker, Jan 12 2015
a(n) = a(n-1) + a(n-2) + a(n-3).
a(n) = A001590(n+1) * 12, for n>=4.
a(n) = A196700(n) * 6, for n>=4. - Alois P. Heinz, Jan 12 2015

Extensions

a(0)-a(3) from M. F. Hasler, Jan 13 2015
Showing 1-5 of 5 results.