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 1-4 of 4 results.

A086347 On a 3 X 3 board, number of n-move routes of chess king ending in a given side square.

Original entry on oeis.org

1, 5, 24, 116, 560, 2704, 13056, 63040, 304384, 1469696, 7096320, 34264064, 165441536, 798822400, 3857055744, 18623512576, 89922273280, 434183143424, 2096421666816, 10122419240960, 48875363631104, 235991131488256, 1139465980477440, 5501828447862784
Offset: 0

Views

Author

Zak Seidov, Jul 17 2003

Keywords

Comments

Number of aa-avoiding words of length n on alphabet {a,b,c,d,e}. - Tanya Khovanova, Jan 11 2007
Binomial transform of A164589 and second binomial transform of A096886. [Al Hakanson (hawkuu(AT)gmail.com), Aug 17 2009]
From Johannes W. Meijer, Aug 01 2010: (Start)
The a(n) represent the number of n-move paths of a chess king on a 3 X 3 board that end or start in a given side square m (m = 2, 4, 6, 8).
Inverse binomial transform of A001109 (without the leading 0).
(End)
Number of independent vertex subsets of the graph obtained by attaching two pendant edges to each vertex of the path graph P_n (see A235116). Example: a(1)=5; indeed, P_1 is the one-vertex graph and after attaching two pendant vertices we obtain the path graph ABC; the independent vertex subsets are: empty, {A}, {B}, {C}, and {A,C}.
Number of simple paths from corner to diagonally opposite corner on a 2 X n grid with king moves allowed. - Andrew Howroyd, Nov 06 2019
Number of 4-compositions of n+1 restricted to parts 1 and 2 (and allowed zeros); see Hopkins & Ouvry reference. - Brian Hopkins, Aug 16 2020

Examples

			a(3) = 116 = 5^3 - 9 (aaa, aab, aac, aad, aae, baa, caa, daa, eaa). [Al Hakanson (hawkuu(AT)gmail.com), Aug 17 2009]
		

Crossrefs

Row 2 of A329118.
Row sums of A235113.
Cf. A028859.
Cf. A126473. - Johannes W. Meijer, Aug 01 2010

Programs

  • Maple
    with(LinearAlgebra): nmax:=19; m:=2; A[5]:= [1,1,1,1,0,1,1,1,1]: A:=Matrix([[0,1,0,1,1,0,0,0,0],[1,0,1,1,1,1,0,0,0],[0,1,0,0,1,1,0,0,0],[1,1,0,0,1,0,1,1,0],A[5],[0,1,1,0,1,0,0,1,1],[0,0,0,1,1,0,0,1,0],[0,0,0,1,1,1,1,0,1],[0,0,0,0,1,1,0,1,0]]): for n from 0 to nmax do B(n):=A^n: a(n):= add(B(n)[m,k],k=1..9): od: seq(a(n), n=0..nmax); # Johannes W. Meijer, Aug 01 2010
    # second Maple program:
    a:= n-> (<<0|1>, <4|4>>^n. <<1, 5>>)[1,1]:
    seq(a(n), n=0..30);  # Alois P. Heinz, Oct 12 2022
  • Mathematica
    Table[(Sqrt[2]/32)((2+Sqrt[8])^(n+2)-(2-Sqrt[8])^(n+2)), {n, 0, 19}]

Formula

a(n) = (sqrt(2)/32)*((2+sqrt(8))^(n+2)-(2-sqrt(8))^(n+2)).
From Ralf Stephan, Feb 01 2004: (Start)
G.f.: (1+x)/(1-4*x-4*x^2).
a(n) = A057087(n) + A057087(n-1). (End)
a(n) = 4*a(n-1) + 4*a(n-2). - Tanya Khovanova, Jan 11 2007
Limit_{k->oo} a(n+k)/a(k) = A084128(n) + 2*A057087(n-1)*sqrt(2). - Johannes W. Meijer, Aug 01 2010
E.g.f.: exp(2*x)*(4*cosh(2*sqrt(2)*x) + 3*sqrt(2)*sinh(2*sqrt(2)*x))/4. - Stefano Spezia, Mar 17 2025

Extensions

Offset changed and edited by Johannes W. Meijer, Jul 15 2010

A164591 a(n) = ((4 + sqrt(18))*(4 + sqrt(8))^n + (4 - sqrt(18))*(4 - sqrt(8))^n)/8 .

Original entry on oeis.org

1, 7, 48, 328, 2240, 15296, 104448, 713216, 4870144, 33255424, 227082240, 1550614528, 10588258304, 72301150208, 493703135232, 3371215880192, 23020101959680, 157191088635904, 1073367893409792, 7329414438191104, 50048372358250496
Offset: 0

Views

Author

Al Hakanson (hawkuu(AT)gmail.com), Aug 17 2009

Keywords

Comments

Binomial transform of A001109 without initial 0. Fourth binomial transform of A096886. Inverse binomial transform of A164592.

Crossrefs

Programs

  • Magma
    Z:=PolynomialRing(Integers()); N:=NumberField(x^2-2); S:=[ ((4+3*r)*(4+2*r)^n+(4-3*r)*(4-2*r)^n)/8: n in [0..19] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Aug 24 2009
    
  • Mathematica
    LinearRecurrence[{8,-8}, {1,7}, 50] (* G. C. Greubel, Aug 12 2017 *)
  • PARI
    Vec((1-x)/(1-8*x+8*x^2)+O(x^99)) \\ Charles R Greathouse IV, Jul 16 2011

Formula

a(n) = 8*a(n-1) - 8*a(n-2) for n > 1; a(0) = 1, a(1) = 7.
G.f.: (1-x)/(1-8*x+8*x^2).
E.g.f.: (1/4)*exp(4*x)*(4*cosh(2*sqrt(2)*x) + 3*sqrt(2)*sinh(2*sqrt(2)*x)). - G. C. Greubel, Aug 12 2017

Extensions

Extended by Klaus Brockhaus and R. J. Mathar Aug 24 2009

A164589 a(n) = ((4 + 3*sqrt(2))*(1 + 2*sqrt(2))^n + (4 - 3*sqrt(2))*(1 - 2*sqrt(2))^n)/8.

Original entry on oeis.org

1, 4, 15, 58, 221, 848, 3243, 12422, 47545, 182044, 696903, 2668114, 10214549, 39105896, 149713635, 573168542, 2194332529, 8400844852, 32162017407, 123129948778, 471394019405, 1804697680256, 6909153496347, 26451190754486, 101266455983401, 387691247248204
Offset: 0

Views

Author

Al Hakanson (hawkuu(AT)gmail.com), Aug 17 2009

Keywords

Comments

Binomial transform of A096886. Inverse binomial transform of A086347.

Crossrefs

Programs

  • Magma
    Z:=PolynomialRing(Integers()); N:=NumberField(x^2-2); S:=[ ((4+3*r)*(1+2*r)^n+(4-3*r)*(1-2*r)^n)/8: n in [0..23] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Aug 24 2009
    
  • Mathematica
    CoefficientList[Series[(1+2x)/(1-2x-7x^2),{x,0,30}],x] (* or *) LinearRecurrence[{2,7},{1,4},30] (* Harvey P. Dale, Jun 22 2011 *)
  • PARI
    Vec((1+2*x)/(1-2*x-7*x^2)+O(x^99)) \\ Charles R Greathouse IV, Jul 16 2011

Formula

a(n) = 2*a(n-1) + 7*a(n-2) for n > 1; a(0) = 1, a(1) = 4.
G.f.: (1 + 2*x)/(1 - 2*x - 7*x^2).
E.g.f.: (1/4)*exp(x)*(4*cosh(2*sqrt(2)*x) + 3*sqrt(2)*sinh(2*sqrt(2)*x)). - G. C. Greubel, Aug 12 2017

Extensions

Edited and extended beyond a(5) by Klaus Brockhaus and R. J. Mathar, Aug 24 2009

A164592 a(n) = 10*a(n-1) - 17*a(n-2) for n > 1; a(0) = 1, a(1) = 8.

Original entry on oeis.org

1, 8, 63, 494, 3869, 30292, 237147, 1856506, 14533561, 113775008, 890679543, 6972620294, 54584650709, 427311962092, 3345180558867, 26187502233106, 205006952830321, 1604881990340408, 12563701705288623, 98354023217099294, 769957303181086349, 6027554637120175492
Offset: 0

Views

Author

Al Hakanson (hawkuu(AT)gmail.com), Aug 17 2009

Keywords

Comments

Binomial transform of A164591. Fifth binomial transform of A096886.

Crossrefs

Programs

  • Magma
    Z:=PolynomialRing(Integers()); N:=NumberField(x^2-2); S:=[ ((4+3*r)*(5+2*r)^n+(4-3*r)*(5-2*r)^n)/8: n in [0..19] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Aug 24 2009
    
  • Mathematica
    CoefficientList[Series[(1 - 2*z)/(17*z^2 - 10*z + 1), {z, 0, 200}], z] (* Vladimir Joseph Stephan Orlovsky, Jun 12 2011 *)
    LinearRecurrence[{10,-17},{1,8},30] (* Harvey P. Dale, Oct 14 2012 *)
  • PARI
    my(x='x+O('x^30)); Vec((1-2*x)/(1-10*x+17*x^2)) \\ G. C. Greubel, Aug 12 2017

Formula

a(n) = 10*a(n-1) - 17*a(n-2) for n > 1; a(0) = 1, a(1) = 8.
a(n) = ((4 + sqrt(18))*(5 + sqrt(8))^n + (4 - sqrt(18))*(5 - sqrt(8))^n)/8.
G.f.: (1-2*x)/(1-10*x+17*x^2).
E.g.f.: (1/4)*exp(5*x)*(4*cosh(2*sqrt(2)*x) + 3*sqrt(2)*sinh(2*sqrt(2)*x)). - G. C. Greubel, Aug 12 2017

Extensions

Extended by Klaus Brockhaus and R. J. Mathar Aug 24 2009
Showing 1-4 of 4 results.