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.

A051927 Number of independent vertex sets in the n-prism graph Y_n = K_2 X C_n (n > 2).

Original entry on oeis.org

3, 1, 7, 13, 35, 81, 199, 477, 1155, 2785, 6727, 16237, 39203, 94641, 228487, 551613, 1331715, 3215041, 7761799, 18738637, 45239075, 109216785, 263672647, 636562077, 1536796803, 3710155681, 8957108167, 21624372013, 52205852195
Offset: 0

Views

Author

Stephen G Penrice, Dec 19 1999

Keywords

Comments

For n>1, a(n) is also the number of ways to place k non-attacking wazirs on a 2 X n horizontal cylinder, summed over all k>=0 (wazir is a leaper [0,1]). - Vaclav Kotesovec, May 08 2012
Also the number of vertex covers for Y_n. - Eric W. Weisstein, Jan 04 2014

Crossrefs

Column 2 of A286513 and row 2 of A287376.

Programs

  • Magma
    I:=[3, 1, 7]; [n le 3 select I[n] else Self(n-1) + 3*Self(n-2) + Self(n-3): n in [1..30]]; // Vincenzo Librandi, May 04 2013
    
  • Maple
    A051927 := x -> (1+sqrt(2))^x+(-1)^x+(1-sqrt(2))^x;
    seq(simplify(A051927(i)),i=0..28); # Peter Luschny, Aug 13 2012
  • Mathematica
    CoefficientList[Series[(3 - 2 x - 3 x^2) / ((1 - 2 x - x^2) (1 + x)), {x, 0, 40}], x] (* Vincenzo Librandi, May 04 2013 *)
    Table[LucasL[n, 2] + (-1)^n, {n, 0, 20}] (* Vladimir Reshetnikov, Sep 15 2016 *)
    LinearRecurrence[{1, 3, 1}, {1, 7, 13}, {0, 20}] (* Eric W. Weisstein, Sep 27 2017 *)
  • PARI
    a(n)=polcoeff((3-2*x-3*x^2)/(1-2*x-x^2)/(1+x)+x*O(x^n),n)
    
  • PARI
    x='x+O('x^66); Vec( (3-2*x-3*x^2)/((1-2*x-x^2)*(1+x)) ) \\ Joerg Arndt, May 04 2013
  • Sage
    def A051927(x) : return (1+sqrt(2))^x+(-1)^x+(1-sqrt(2))^x
    [A051927(i).round() for i in (0..28)] # Peter Luschny, Aug 13 2012
    

Formula

a(n) = a(n-1) + 3*a(n-2) + a(n-3).
G.f.: (3-2x-3x^2)/((1-2x-x^2)(1+x)). - Michael Somos, Apr 07 2003
Let A=[0, 1, 1;1, 1, 1;1, 1, 0] be the adjacency matrix of a triangle with a loop at a vertex. Then a(n)=trace(A^n). a(n)=(-1)^n+(1-sqrt(2))^n+(1+sqrt(2))^n. - Paul Barry, Jul 22 2004
a(n) = A002203(n) + (-1)^n. - Vladimir Reshetnikov, Sep 15 2016
a(n)+a(n+1) = 4*A000129(n+1). - R. J. Mathar, Feb 13 2020
E.g.f.: cosh(x) + 2*exp(x)*cosh(sqrt(2)*x) - sinh(x). - Stefano Spezia, Mar 31 2024

A286514 Array read by antidiagonals: T(m,n) = number of dominating sets in the stacked prism graph C_m X P_n.

Original entry on oeis.org

1, 3, 3, 5, 11, 7, 9, 41, 51, 11, 17, 149, 383, 183, 21, 31, 547, 2865, 2629, 663, 39, 57, 2007, 21449, 38437, 18635, 2435, 71, 105, 7361, 160579, 561743, 531669, 133709, 8935, 131, 193, 27001, 1202181, 8207075, 15179657, 7455797, 956009, 32775, 241
Offset: 1

Views

Author

Andrew Howroyd, May 10 2017

Keywords

Examples

			Table starts:
===========================================================
m\n|  1    2      3         4           5             6
---|-------------------------------------------------------
1  |  1    3      5         9          17            31 ...
2  |  3   11     41       149         547          2007 ...
3  |  7   51    383      2865       21449        160579 ...
4  | 11  183   2629     38437      561743       8207075 ...
5  | 21  663  18635    531669    15179657     433200191 ...
6  | 39 2435 133709   7455797   416118655   23213149395 ...
7  | 71 8935 956009 104209625 11369806353 1239821606103 ...
...
		

Crossrefs

Column 2 is A284702.
Row 3 is A285880.
Main diagonal is A286914.
Cf. A286513, A218354 (P_n X P_n).

A212270 Number of ways to place k non-attacking wazirs on an n x n cylindrical chessboard, summed over all k >= 0.

Original entry on oeis.org

2, 7, 43, 933, 36211, 3557711, 746156517, 363549830913, 394677987525997, 974602314570939359, 5418730454986467701985, 68176187476467835406646029, 1936241516342334422813929891295, 124281423643836238320564876791634465, 18018270577720149773239661332878801006033
Offset: 1

Views

Author

Vaclav Kotesovec, May 12 2012

Keywords

Comments

Wazir is a leaper [0,1].

Crossrefs

Main diagonal of A286513.

Formula

Limit n ->infinity (a(n))^(1/n^2) is the hard square entropy constant A085850.

A050400 Number of independent sets of vertices in P_3 X C_n (n > 2).

Original entry on oeis.org

5, 1, 17, 43, 181, 621, 2309, 8303, 30277, 109753, 398857, 1447931, 5258725, 19095285, 69344061, 251811903, 914429445, 3320635025, 12058502657, 43789003563, 159014593621, 577442573597, 2096914206261, 7614694850543, 27651860345029, 100414447219721, 364643142303353
Offset: 0

Views

Author

Stephen G Penrice, Dec 21 1999

Keywords

Crossrefs

Column 3 of A286513.

Programs

  • GAP
    a:=[5,1,17,43,181];; for n in [6..30] do a[n]:=a[n-1]+8*a[n-2] +6*a[n-3] -a[n-4]-a[n-5]; od; a; # G. C. Greubel, Oct 30 2019
  • Magma
    I:=[5,1,17,43,181]; [n le 5 select I[n] else Self(n-1) + 8*Self(n-2) + 6*Self(n-3) - Self(n-4) - Self(n-5): n in [1..30]]; // Vincenzo Librandi, May 11 2017
    
  • Maple
    seq(coeff(series((5-4*x-24*x^2-12*x^3+x^4)/((1+x)*(1-2*x-6*x^2+x^4)), x, n+1), x, n), n = 0..30); # G. C. Greubel, Oct 30 2019
  • Mathematica
    CoefficientList[Series[(5-4*x-24*x^2-12*x^3+x^4)/((1+x)*(1-2*x-6*x^2+ x^4)), {x, 0, 30}], x] (* Vincenzo Librandi, May 11 2017 *)
  • PARI
    my(x='x+O('x^30)); Vec((5-4*x-24*x^2-12*x^3+x^4)/((1+x)*(1-2*x-6*x^2+x^4))) \\ G. C. Greubel, Oct 30 2019
    
  • Sage
    def A077952_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P((5-4*x-24*x^2-12*x^3+x^4)/((1+x)*(1-2*x-6*x^2+x^4))).list()
    A077952_list(30) # G. C. Greubel, Oct 30 2019
    

Formula

a(n) = a(n-1) + 8*a(n-2) + 6*a(n-3) - a(n-4) - a(n-5).
G.f.: (5-4*x-24*x^2-12*x^3+x^4)/((1+x)*(1-2*x-6*x^2+x^4)). - Maksym Voznyy (voznyy(AT)mail.ru), Aug 12 2009

Extensions

More terms from Michael Lugo (mlugo(AT)thelabelguy.com), Dec 22 1999

A050401 Number of independent sets of nodes in P_4 X C_n (n > 2).

Original entry on oeis.org

8, 1, 41, 142, 933, 4741, 26660, 143697, 788453, 4293286, 23454801, 127953981, 698467368, 3811712633, 20803963753, 113540081302, 619672701957, 3381980484909, 18457878595412, 100737602247769, 549796303339413
Offset: 0

Views

Author

Stephen G Penrice, Dec 21 1999

Keywords

Crossrefs

Column 4 of A286513.

Programs

  • GAP
    a:=[8,1,41,142,933,4741,26660,143697];; for n in [9..30] do a[n]:= a[n-1]+20*a[n-2]+27*a[n-3]-14*a[n-4]-25*a[n-5]+4*a[n-6]+5*a[n-7]-a[n-8]; od; a; # G. C. Greubel, Oct 30 2019
  • Magma
    I:=[8,1,41,142,933,4741,26660,143697]; [n le 8 select I[n] else Self(n-1)+20*Self(n-2)+27*Self(n-3)-14*Self(n-4)- 25*Self(n-5)+4*Self(n-6)+5*Self(n-7)-Self(n-8): n in [1..30]]; // Vincenzo Librandi, May 11 2017
    
  • Magma
    R:=PowerSeriesRing(Integers(), 30); Coefficients(R!( (8 -7*x -120*x^2 -135*x^3 +56*x^4 +75*x^5 -8*x^6 -5*x^7)/((1+x)*(1+2*x-x^2)*( 1-4*x-9*x^2+5*x^3+4*x^4-x^5)) )); // G. C. Greubel, Oct 30 2019
    
  • Maple
    seq(coeff(series((8 -7*x -120*x^2 -135*x^3 +56*x^4 +75*x^5 -8*x^6 -5*x^7)/( (1+x)*(1+2*x-x^2)*(1-4*x-9*x^2+5*x^3+4*x^4-x^5)), x, n+1), x, n), n = 0 ..30); # G. C. Greubel, Oct 30 2019
  • Mathematica
    CoefficientList[Series[(8-7*x-120*x^2-135*x^3+56*x^4+75*x^5-8*x^6-5*x^7) /( (1+x)*(1+2*x-x^2)*(1-4*x-9*x^2+5*x^3+4*x^4-x^5)), {x, 0, 50}], x] (* Vincenzo Librandi, May 11 2017 *)
  • PARI
    my(x='x+O('x^30)); Vec((8 -7*x -120*x^2 -135*x^3 +56*x^4 +75*x^5 -8*x^6 -5*x^7)/((1+x)*(1+2*x-x^2)*(1-4*x-9*x^2+5*x^3+4*x^4-x^5))) \\ G. C. Greubel, Oct 30 2019
    
  • Sage
    def A050401_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P((8 -7*x -120*x^2 -135*x^3 +56*x^4 +75*x^5 -8*x^6 -5*x^7)/((1+x)*(1+2*x-x^2)*(1-4*x-9*x^2+5*x^3+4*x^4-x^5))).list()
    A050401_list(30) # G. C. Greubel, Oct 30 2019
    

Formula

a(n) = a(n-1) + 20*a(n-2) + 27*a(n-3) - 14*a(n-4) - 25*a(n-5) + 4*a(n-6) + 5*a(n-7) - a(n-8).
G.f.: (8 -7*x -120*x^2 -135*x^3 +56*x^4 +75*x^5 -8*x^6 -5*x^7)/((1+x)*(1+2*x-x^2)*(1-4*x-9*x^2+5*x^3+4*x^4-x^5)). - Colin Barker, Aug 31 2012

Extensions

More terms from Michael Lugo (mlugo(AT)thelabelguy.com), Dec 22 1999

A051926 Number of independent sets of nodes in graph C_4 X P_n (n>2).

Original entry on oeis.org

1, 7, 35, 181, 933, 4811, 24807, 127913, 659561, 3400911, 17536203, 90422365, 466247117, 2404121747, 12396433487, 63920042065, 329592522065, 1699486218903, 8763103574515, 45185411569413, 232990675202677, 1201375684008283, 6194683683674679, 31941803427179001
Offset: 0

Views

Author

Stephen G Penrice, Dec 19 1999

Keywords

Comments

Number of ways zero or more black and white stones can be placed on the points of a 2 X n grid such that no white stones are adjacent to any black stones. A078057 is a related case, where the grid is 1 X n. - Wayne VanWeerthuizen, May 04 2004

Crossrefs

Row 4 of A286513.

Programs

  • Magma
    I:=[1, 7, 35]; [n le 3 select I[n] else 5*Self(n-1)+Self(n-2)-Self(n-3): n in [1..25]]; // Vincenzo Librandi, Apr 27 2012
  • Mathematica
    CoefficientList[Series[(1+2*x-x^2)/(1-5*x-x^2+x^3),{x,0,30}],x] (* Vincenzo Librandi, Apr 27 2012 *)
    LinearRecurrence[{5,1,-1},{1,7,35},40] (* Harvey P. Dale, Apr 29 2019 *)

Formula

a(n) = 5*a(n-1)+a(n-2)-a(n-3) for n>2. - Wayne VanWeerthuizen, May 04 2004
G.f.: (1+2*x-x^2)/(1-5*x-x^2+x^3). - Colin Barker, Apr 18 2012

Extensions

More terms from James Sellers, Dec 20 1999

A181961 Number of independent sets of nodes in graph C_6 x P_n (n>=0).

Original entry on oeis.org

1, 18, 199, 2309, 26660, 307983, 3557711, 41097664, 474748249, 5484153915, 63351353194, 731816432741, 8453730886601, 97655043951558, 1128082705387895, 13031283779122753, 150533605489179940, 1738920490541077131, 20087504465180492695, 232045017488460324836
Offset: 0

Views

Author

Cesar Bautista, Apr 04 2012

Keywords

Crossrefs

Row 6 of A286513.

Programs

Formula

a(n) = 12*a(n-1)-3*a(n-2)-25*a(n-3)-2*a(n-4)+a(n-5) for n>=5, with a(0)=1, a(1)=18, a(2)=199, a(3)=2309, a(4)=26660.
G.f.: (1 + 6*x - 14*x^2 + x^4)/(1 - 12*x + 3*x^2 + 25*x^3 + 2*x^4 - x^5). - Charles R Greathouse IV, Apr 04 2012

A181989 Number of independent sets of nodes in graph C_5 x P_n (n >= 0).

Original entry on oeis.org

1, 11, 81, 621, 4741, 36211, 276561, 2112241, 16132281, 123210611, 941023441, 7187084861, 54891500621, 419234905211, 3201914754721, 24454686308481, 186773143027761, 1426483517982011, 10894795654704401, 83209214029813101, 635511992964231701, 4853735225243983011
Offset: 0

Views

Author

Cesar Bautista, Apr 04 2012

Keywords

Crossrefs

Row 5 of A286513.

Formula

a(n) = 7*a(n-1) + 5*a(n-2) - a(n-3) with a(0)=1, a(1)=11, a(2)=81.
G.f.: (1+4*x-x^2)/(x^3-5*x^2-7*x+1).

A182014 Number of independent sets of nodes in graph C_7 x P_n (n>=0).

Original entry on oeis.org

1, 29, 477, 8303, 143697, 2488431, 43089985, 746156517, 12920616493, 223736359029, 3874270087045, 67087749098875, 1161706844818941, 20116382073294655, 348339884131004417, 6031933298656980345, 104450339960964929961, 1808686034441106749965
Offset: 0

Views

Author

Cesar Bautista, Apr 06 2012

Keywords

Crossrefs

Row 7 of A286513.

Programs

  • Mathematica
    LinearRecurrence[{17,8,-44,5,1},{1,29,477,8303,143697},30] (* Harvey P. Dale, Aug 27 2012 *)
  • PARI
    Vec((x^4+6*x^3-24*x^2+12*x+1)/(-x^5-5*x^4+44*x^3-8*x^2-17*x+1)+O(x^99)) \\ Charles R Greathouse IV, Apr 06 2012

Formula

a(n) = 17*a(n-1) + 8*a(n-2) - 44*a(n-3) + 5*a(n-4) + a(n-5) with a(0)=1, a(1)=29, a(2)=477, a(3)=8303, a(4)=143697.
G.f.: (x^4+6*x^3-24*x^2+12*x+1)/(-x^5-5*x^4+44*x^3-8*x^2-17*x+1).

A182019 Number of independent sets of nodes in graph C_8 x P_n (n>=0).

Original entry on oeis.org

1, 47, 1155, 30277, 788453, 20546803, 535404487, 13951571713, 363549830913, 9473376491295, 246857112567171, 6432599206076589, 167620580643483109, 4367854759124964451, 113817498564834289095, 2965854794621630365713, 77284202988962060229833
Offset: 0

Views

Author

Cesar Bautista, Apr 06 2012

Keywords

Crossrefs

Row 8 of A286513.

Formula

a(n) = 29*a(n-1)-65*a(n-2)-317*a(n-3)+334*a(n-4)+187*a(n-5)-109*a(n-6)+5*a(n-7)+a(n-8) with a(0)=1, a(1)=47,a(2)=1155,a(3)=30277,a(4)=788453, a(5)=20546803, a(6)=535404487, a(7)=13951571713.
G.f.: -(x^7 +4*x^6 -79*x^5 +60*x^4 +154*x^3 -143*x^2 +18*x +1)/(x^8 +5*x^7 -109*x^6 +187*x^5 +334*x^4 -317*x^3 -65*x^2 +29*x -1). [Colin Barker, Aug 31 2012]
Showing 1-10 of 10 results.