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 10 results.

A200781 G.f.: 1/(1-5*x+10*x^3-5*x^4).

Original entry on oeis.org

1, 5, 25, 115, 530, 2425, 11100, 50775, 232275, 1062500, 4860250, 22232375, 101698250, 465201250, 2127983750, 9734098125, 44526969375, 203681015625, 931704015625, 4261920875000, 19495429065625, 89178510250000, 407931862578125, 1866014626609375, 8535765175875000, 39045399804843750, 178606512071015625, 817004981729375000
Offset: 0

Views

Author

R. H. Hardin, Nov 22 2011

Keywords

Comments

Number of words of length n over an alphabet of size 5 which do not contain any strictly decreasing factor (consecutive subword) of length 3. For alphabets of size 2, 3, 4, 6 see A000079, A076264, A072335, A200782.
Equivalently, number of 0..4 arrays x(0..n-1) of n elements without any two consecutive increases.

Examples

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

Crossrefs

The g.f. corresponds to row 5 of triangle A225682.
Column 4 of A200785.

Programs

  • PARI
    Vec(1/(1-5*x+10*x^3-5*x^4) + O(x^30)) \\ Jinyuan Wang, Mar 10 2020

Formula

a(n) = 5*a(n-1) - 10*a(n-3) + 5*a(n-4).

Extensions

Edited by N. J. A. Sloane, May 21 2013

A200782 Expansion of 1 / (1 - 6*x + 20*x^3 - 15*x^4 + x^6).

Original entry on oeis.org

1, 6, 36, 196, 1071, 5796, 31395, 169884, 919413, 4975322, 26924106, 145698840, 788446400, 4266656226, 23088902733, 124944995676, 676136621430, 3658895818470, 19800020091895, 107147296401684, 579824822459421, 3137707025200000
Offset: 0

Views

Author

R. H. Hardin, Nov 22 2011

Keywords

Comments

a(n) is the number of words of length n over an alphabet of size 6 which do not contain any strictly decreasing factor (consecutive subword) of length 3.
Equivalently, dimensions of homogeneous components of the universal associative envelope for a certain nonassociative triple system [Bremner].
This is the g.f. corresponding to row 6 of A225682.

Examples

			a(n) is also the number of words of length n over an alphabet of size 6 which do not contain any strictly increasing factor of length 3. Some solutions for n=5:
..5....5....0....3....2....4....3....3....3....3....0....3....3....1....0....1
..1....5....0....0....4....5....1....1....3....5....1....0....2....0....3....4
..3....5....1....0....4....3....1....4....5....0....1....5....1....0....0....3
..0....0....0....4....1....1....1....4....2....4....1....1....2....5....4....1
..1....4....2....0....0....0....1....3....1....4....3....2....2....2....4....5
		

Crossrefs

Column 5 of A200785.
G.f. corresponds to row 6 of A225682.

Programs

  • Mathematica
    CoefficientList[Series[1 / (1 - 6*x + 20*x^3 - 15*x^4 + x^6), {x, 0, 20}], x] (* Vaclav Kotesovec, Jan 26 2015 *)
    LinearRecurrence[{6,0,-20,15,0,-1},{1,6,36,196,1071,5796},30] (* Harvey P. Dale, Jul 28 2019 *)
  • PARI
    Vec(1/(1-6*x+20*x^3-15*x^4+x^6) + O(x^30)) \\ Michel Marcus, Jan 26 2015

Formula

G.f.: 1 / (1 - 6*x + 20*x^3 - 15*x^4 + x^6).
a(n) = 6*a(n-1) - 20*a(n-3) + 15*a(n-4) - a(n-6).

Extensions

Entry revised by N. J. A. Sloane, May 17 2013, merging this with A225381
Typo in name corrected by Michel Marcus, Jan 26 2015

A200783 G.f.: 1/(1-7*x+35*x^3-35*x^4+7*x^6-x^7).

Original entry on oeis.org

1, 7, 49, 308, 1946, 12152, 75992, 474566, 2964416, 18514405, 115637431, 722234149, 4510869636, 28173535572, 175963587528, 1099016234232, 6864129384252, 42871313869692, 267761500599901, 1672358840069239, 10445056851917149, 65236724277810632, 407449213173792062, 2544806826734163992, 15894107968042546424, 99269879914558590146
Offset: 0

Views

Author

R. H. Hardin Nov 22 2011

Keywords

Comments

Number of words of length n over an alphabet of size 7 which do not contain any strictly decreasing factor (consecutive subword) of length 3.
Number of 0..6 arrays x(0..n-1) of n elements without any two consecutive increases.

Examples

			Some solutions for n=5
..6....2....6....3....4....4....6....6....5....3....2....4....5....0....5....5
..4....5....0....4....1....6....4....5....1....1....2....6....6....6....3....6
..4....4....0....4....5....3....5....5....5....1....5....3....3....6....4....2
..3....6....2....5....5....2....2....4....5....5....3....3....2....1....4....5
..4....5....0....3....1....0....4....3....5....5....2....1....0....0....5....3
		

Crossrefs

Column 6 of A200785.
G.f. corresponds to row 7 of A225682.

Programs

  • Mathematica
    CoefficientList[Series[1/(1-7x+35x^3-35x^4+7x^6-x^7),{x,0,30}],x] (* or *) LinearRecurrence[{7,0,-35,35,0,-7,1},{1,7,49,308,1946,12152,75992},30] (* Harvey P. Dale, Jul 23 2014 *)

Formula

a(n) = 7*a(n-1) - 35*a(n-3) + 35*a(n-4) - 7*a(n-6) + a(n-7).

Extensions

Edited by N. J. A. Sloane, May 21 2013

A200784 Number of 0..7 arrays x(0..n+1) of n+2 elements without any two consecutive increases.

Original entry on oeis.org

456, 3270, 23136, 164004, 1160616, 8216484, 58154912, 411637168, 2913595712, 20622837480, 145970677056, 1033197881712, 7313093248992, 51762926098992, 366383987227392, 2593308396911680, 18355737644921600, 129924040926296800
Offset: 1

Views

Author

R. H. Hardin, Nov 22 2011

Keywords

Comments

Column 7 of A200785.

Examples

			Some solutions for n=3
..7....5....7....4....5....2....3....7....5....5....5....6....1....5....4....4
..0....5....4....2....3....2....1....4....0....5....7....4....0....5....4....4
..0....5....4....1....6....6....3....5....0....4....6....6....6....7....4....4
..0....1....7....1....5....5....0....0....6....1....6....3....0....0....4....7
..1....4....0....6....5....2....6....5....3....4....2....4....1....2....4....3
		

Formula

Empirical: a(n) = 8*a(n-1) -56*a(n-3) +70*a(n-4) -28*a(n-6) +8*a(n-7).
Empirical g.f.: 2*x*(228 - 189*x - 1512*x^2 + 2226*x^3 - 108*x^4 - 864*x^5 + 256*x^6) / ((1 - 2*x)*(1 + 2*x - 2*x^2)*(1 - 8*x + 6*x^2 + 4*x^3 - 2*x^4)). - Colin Barker, Oct 15 2017

A200786 Number of 0..n arrays x(0..3) of 4 elements without any two consecutive increases.

Original entry on oeis.org

16, 75, 225, 530, 1071, 1946, 3270, 5175, 7810, 11341, 15951, 21840, 29225, 38340, 49436, 62781, 78660, 97375, 119245, 144606, 173811, 207230, 245250, 288275, 336726, 391041, 451675, 519100, 593805, 676296, 767096, 866745, 975800, 1094835
Offset: 1

Views

Author

R. H. Hardin, Nov 22 2011

Keywords

Comments

Row 2 of A200785.

Examples

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

Formula

Empirical: a(n) = (17/24)*n^4 + (43/12)*n^3 + (151/24)*n^2 + (53/12)*n + 1.
Conjectures from Colin Barker, Oct 15 2017: (Start)
G.f.: x*(16 - 5*x + 10*x^2 - 5*x^3 + x^4) / (1 - x)^5.
a(n) = (24 + 106*n + 151*n^2 + 86*n^3 + 17*n^4) / 24.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.
(End)

A200787 Number of 0..n arrays x(0..4) of 5 elements without any two consecutive increases.

Original entry on oeis.org

32, 216, 840, 2425, 5796, 12152, 23136, 40905, 68200, 108416, 165672, 244881, 351820, 493200, 676736, 911217, 1206576, 1573960, 2025800, 2575881, 3239412, 4033096, 4975200, 6085625, 7385976, 8899632, 10651816, 12669665, 14982300
Offset: 1

Views

Author

R. H. Hardin, Nov 22 2011

Keywords

Comments

Row 3 of A200785.

Examples

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

Formula

Empirical: a(n) = (7/12)*n^5 + (47/12)*n^4 + (39/4)*n^3 + (133/12)*n^2 + (17/3)*n + 1.
Conjectures from Colin Barker, Oct 15 2017: (Start)
G.f.: x*(32 + 24*x + 24*x^2 - 15*x^3 + 6*x^4 - x^5) / (1 - x)^6.
a(n) = (1 + n)^2*(12 + 44*n + 33*n^2 + 7*n^3) / 12 .
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.
(End)

A200788 Number of 0..n arrays x(0..5) of 6 elements without any two consecutive increases.

Original entry on oeis.org

64, 622, 3136, 11100, 31395, 75992, 164004, 324087, 597190, 1039654, 1726660, 2756026, 4252353, 6371520, 9305528, 13287693, 18598188, 25569934, 34594840, 46130392, 60706591, 78933240, 101507580, 129222275, 162973746, 203770854
Offset: 1

Views

Author

R. H. Hardin, Nov 22 2011

Keywords

Comments

Row 4 of A200785.

Examples

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

Formula

Empirical: a(n) = (349/720)*n^6 + (321/80)*n^5 + (1883/144)*n^4 + (1013/48)*n^3 + (3139/180)*n^2 + (413/60)*n + 1.
Conjectures from Colin Barker, Oct 15 2017: (Start)
G.f.: x*(64 + 174*x + 126*x^2 - 30*x^3 + 21*x^4 - 7*x^5 + x^6) / (1 - x)^7.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7.
(End)

A200789 Number of 0..n arrays x(0..6) of 7 elements without any two consecutive increases.

Original entry on oeis.org

128, 1791, 11704, 50775, 169884, 474566, 1160616, 2562633, 5217520, 9944957, 17946864, 30927871, 51238812, 82045260, 127523120, 193083297, 285627456, 413836891, 588496520, 822856023, 1133030140, 1538440146, 2062298520
Offset: 1

Views

Author

R. H. Hardin, Nov 22 2011

Keywords

Comments

Row 5 of A200785.

Examples

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

Formula

Empirical: a(n) = (2017/5040)*n^7 + (1427/360)*n^6 + (5759/360)*n^5 + (607/18)*n^4 + (28459/720)*n^3 + (9113/360)*n^2 + (848/105)*n + 1.
Conjectures from Colin Barker, Oct 15 2017: (Start)
The formulas below are consistent with the conjectured formula above.
G.f.: x*(128 + 767*x + 960*x^2 + 123*x^3 + 60*x^4 - 28*x^5 + 8*x^6 - x^7) / (1 - x)^8.
a(n) = (5040 + 40704*n + 127582*n^2 + 199213*n^3 + 169960*n^4 + 80626*n^5 + 19978*n^6 + 2017*n^7) / 5040.
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.
(End)

A200790 Number of 0..n arrays x(0..7) of 8 elements without any two consecutive increases.

Original entry on oeis.org

256, 5157, 43681, 232275, 919413, 2964416, 8216484, 20273247, 45611500, 95196145, 186686721, 347374261, 617994573, 1057577400, 1749504272, 2808961221, 4391985888, 6706321909, 10024306825, 14698033119, 21177035341, 30028769640
Offset: 1

Views

Author

R. H. Hardin, Nov 22 2011

Keywords

Comments

Row 6 of A200785.

Examples

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

Formula

Empirical: a(n) = (6679/20160)*n^8 + (4799/1260)*n^7 + (26449/1440)*n^6 + (2162/45)*n^5 + (212153/2880)*n^4 + (6019/90)*n^3 + (174571/5040)*n^2 + (3893/420)*n + 1.
Conjectures from Colin Barker, Oct 15 2017: (Start)
G.f.: x*(256 + 2853*x + 6484*x^2 + 3294*x^3 + 522*x^4 - 79*x^5 + 36*x^6 - 9*x^7 + x^8) / (1 - x)^9.
a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9) for n>9.
(End)

A200791 Number of 0..n arrays x(0..8) of 9 elements without any two consecutive increases.

Original entry on oeis.org

512, 14849, 163020, 1062500, 4975322, 18514405, 58154912, 160338680, 398601390, 910893148, 1941103528, 3899741885, 7449762880, 13624665670, 23987233104, 40838614531, 67488892468, 108601809395, 170627966340, 262342539690
Offset: 1

Views

Author

R. H. Hardin, Nov 22 2011

Keywords

Comments

Row 7 of A200785.

Examples

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

Formula

Empirical: a(n) = (99377/362880)*n^9 + (48247/13440)*n^8 + (243673/12096)*n^7 + (60529/960)*n^6 + (2076437/17280)*n^5 + (274529/1920)*n^4 + (952027/9072)*n^3 + (152461/3360)*n^2 + (26399/2520)*n + 1.
Conjectures from Colin Barker, Oct 15 2017: (Start)
G.f.: x*(512 + 9729*x + 37570*x^2 + 39065*x^3 + 11862*x^4 + 551*x^5 + 124*x^6 - 45*x^7 + 10*x^8 - x^9) / (1 - x)^10.
a(n) = 10*a(n-1) - 45*a(n-2) + 120*a(n-3) - 210*a(n-4) + 252*a(n-5) - 210*a(n-6) + 120*a(n-7) - 45*a(n-8) + 10*a(n-9) - a(n-10) for n>10.
(End)
Showing 1-10 of 10 results.