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.

Previous Showing 11-19 of 19 results.

A167375 a(n)=3*a(n-1)-a(n-2) with a(0)=1, a(1)=3, a(2)=11.

Original entry on oeis.org

1, 3, 11, 30, 79, 207, 542, 1419, 3715, 9726, 25463, 66663, 174526, 456915, 1196219, 3131742, 8199007, 21465279, 56196830, 147125211, 385178803, 1008411198, 2640054791, 6911753175, 18095204734, 47373861027, 124026378347, 324705274014, 850089443695
Offset: 0

Views

Author

Jamel Ghanouchi, Nov 02 2009

Keywords

Crossrefs

Programs

  • Magma
    I:=[1,3,11]; [n le 3 select I[n] else 3*Self(n-1)-Self(n-2): n in [1..50]]; // Vincenzo Librandi, Jun 26 2014
  • Mathematica
    Join[{1},LinearRecurrence[{3,-1},{3,11},30]] (* Harvey P. Dale, Jun 25 2014 *)
    CoefficientList[Series[(3 x^2 + 1)/(1 - 3 x + x^2), {x, 0, 40}], x] (* Vincenzo Librandi, Jun 26 2014 *)
    Table[3LucasL[2n+1]-Fibonacci[2n], {n,0,20}] (* Rigoberto Florez, Dec 24 2018 *)

Formula

a(n) = (-1)^n*A098150(n-1), n>0.
G.f.: (3*x^2+1)/(1-3*x+x^2).
a(n) = 3*L(2n+1)-F(2n), where F(n) is the n-th Fibonacci number and L(n) is the n-th Lucas number. - Rigoberto Florez, Dec 24 2018

Extensions

Edited by R. J. Mathar, Nov 03 2009

A167387 a(n) = (-1)^(n+1) * n*(n-1)*(n-4)*(n+1)/12.

Original entry on oeis.org

1, -2, 0, 10, -35, 84, -168, 300, -495, 770, -1144, 1638, -2275, 3080, -4080, 5304, -6783, 8550, -10640, 13090, -15939, 19228, -23000, 27300, -32175, 37674, -43848, 50750, -58435, 66960, -76384, 86768, -98175, 110670, -124320, 139194, -155363, 172900
Offset: 2

Views

Author

Jamel Ghanouchi, Nov 02 2009

Keywords

Comments

The coefficient of [x^4] of the Polynomial B_{2n}(x) defined in A137276.
Essentially the same as A052472.

Crossrefs

Programs

  • GAP
    List([2..40], n-> (-1)^(n+1)*(n-4)*Binomial(n+1,3)/2); # G. C. Greubel, May 19 2019
  • Magma
    [(-1)^(n+1)*n*(n-1)*(n-4)*(n+1)/12: n in [2..40]]; // Vincenzo Librandi, Jun 13 2016
    
  • Mathematica
    Table[(-1)^(n+1)*(n+1)*n*(n-1)*(n-4)/12, {n, 2, 40}] (* G. C. Greubel, Jun 12 2016 *)
    LinearRecurrence[{-5, -10, -10, -5, -1}, {1, -2, 0, 10, -35}, 40] (* Vincenzo Librandi, Jun 13 2016 *)
  • PARI
    vector(40, n, n++; (-1)^(n+1)*(n-4)*binomial(n+1,3)/2) \\ G. C. Greubel, May 19 2019
    
  • Sage
    [(-1)^(n+1)*(n-4)*binomial(n+1,3)/2 for n in (2..40)] # G. C. Greubel, May 19 2019
    

Formula

a(n) = -5*a(n-1) -10*a(n-2) -10*a(n-3) -5*a(n-4) -a(n-5).
G.f.: x^2*(1+3*x)/(1+x)^5.
E.g.f.: x^2*(6 + 2*x - x^2)*exp(-x)/12. - G. C. Greubel, May 19 2019

A167543 a(n) = (n-5)*(n-6)*(n-7)*(n-16)/24.

Original entry on oeis.org

-2, -7, -15, -25, -35, -42, -42, -30, 0, 55, 143, 273, 455, 700, 1020, 1428, 1938, 2565, 3325, 4235, 5313, 6578, 8050, 9750, 11700, 13923, 16443, 19285, 22475, 26040, 30008, 34408, 39270, 44625, 50505, 56943, 63973, 71630, 79950, 88970, 98728, 109263, 120615
Offset: 8

Views

Author

Jamel Ghanouchi, Nov 06 2009

Keywords

Crossrefs

Programs

  • Magma
    [Binomial(n-5,3)*(n-16)/4: n in [8..60]]; // G. C. Greubel, Jul 30 2022
    
  • Mathematica
    Table[(n-5)*(n-6)*(n-7)*(n-16)/24, {n,8,60}] (* G. C. Greubel, Jun 15 2016 *)
  • SageMath
    [binomial(n-5,3)*(n-16)/4 for n in (8..60)] # G. C. Greubel, Jul 30 2022

Formula

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5).
G.f.: x^8*(-2+3*x)/(1-x)^5.
E.g.f.: (1/24)*( -3360 - 1800*x - 420*x^2 - 52*x^3 - 3*x^4 + (3360 - 1560*x + 300*x^2 - 28*x^3 + x^4)*exp(x) ). - G. C. Greubel, Jul 30 2022

Extensions

Definition simplified, sequence extended by R. J. Mathar, Nov 12 2009

A136255 Triangle T(n,k) read by rows: T(n,k) = (k+1) * A137276(n,k+1).

Original entry on oeis.org

1, 0, 2, 1, 0, 3, 0, 0, 0, 4, -3, 0, -3, 0, 5, 0, -6, 0, -8, 0, 6, 5, 0, -6, 0, -15, 0, 7, 0, 16, 0, 0, 0, -24, 0, 8, -7, 0, 30, 0, 15, 0, -35, 0, 9, 0, -30, 0, 40, 0, 42, 0, -48, 0, 10, 9, 0, -75, 0, 35, 0, 84, 0, -63, 0, 11
Offset: 1

Views

Author

Roger L. Bagula, Mar 17 2008

Keywords

Comments

Row sums are 1, 2, 4, 4, -1, -8, -9, 0, 12, 14, 1, ... with g.f. x*(1+3*x^2) / (x^2-x+1)^2.

Examples

			Triangle starts:
{1},
{0, 2},
{1, 0, 3},
{0, 0, 0, 4},
{-3, 0, -3, 0, 5},
{0, -6, 0, -8, 0, 6},
{5, 0, -6, 0, -15, 0, 7},
{0, 16, 0, 0, 0, -24, 0, 8},
{-7, 0, 30, 0, 15, 0, -35, 0, 9},
{0, -30, 0, 40, 0,42, 0, -48, 0, 10},
{9, 0, -75, 0, 35, 0, 84, 0, -63, 0, 11},
...
		

Crossrefs

Programs

  • Maple
    B := proc(n,x) if n = 0 then 1; else add( (-1)^j*binomial(n-j,j)*(n-4*j)/(n-j)*x^(n-2*j),j=0..n/2) ; fi; end:
    A136255 := proc(n,k) diff( B(n,x),x) ; coeftayl(%,x=0,k) ; end: seq( seq(A136255(n,k),k=0..n-1),n=1..15) ;
  • Mathematica
    B[x, 0] = 1; B[x, 1] = x; B[x, 2] = 2 + x^2; B[x, 3] = x + x^3; B[x, 4] = -2 + x^4; B[x_, n_] := B[x, n] = x*B[x, n-1] - B[x, n-2]; P[x_, n_] := D[B[x, n + 1], x]; Flatten @ Table[CoefficientList[P[x, n], x], {n, 0, 10}]

Formula

T(n,k) = (k+1) * A137276(n,k+1) .

Extensions

Edited by the Associate Editors of the OEIS, Aug 27 2009
Edited by and new name from Joerg Arndt, May 15 2016

A195662 Triangle T(n,k) read by rows: T(0,0)= -3, T(1,0)= 2, T(1,1) = 0 and T(n,k) = T(n-1,k) -T(n-2,k-2) otherwise.

Original entry on oeis.org

-3, 2, 0, 2, 0, 3, 2, 0, 1, 0, 2, 0, -1, 0, -3, 2, 0, -3, 0, -4, 0, 2, 0, -5, 0, -3, 0, 3, 2, 0, -7, 0, 0, 0, 7, 0, 2, 0, -9, 0, 5, 0, 10, 0, -3, 2, 0, -11, 0, 12, 0, 10, 0, -10, 0, 2, 0, -13, 0, 21, 0, 5, 0, -20, 0, 3, 2, 0, -15, 0, 32, 0, -7, 0, -30, 0, 13, 0
Offset: 0

Views

Author

Paul Curtz, Sep 22 2011

Keywords

Comments

In the notation of A195673, this defines polynomials P(n,x,p=-3,q=2), where p and q are the values of the constant and linear order for n=0 and 1.
Row sums -- the value P(n,1,-3,2) of the polynomial -- are A130848(n+5).
For general seed values in the two top rows of the triangle, the recurrence T(n,k) = T(n-1,k) - T(n-2,k-2) defines the triangle
p;
q, 0;
q, 0, -p;
q, 0, -p-q, 0;
q, 0, -p-2q, 0, p;
q, 0, -p-3q, 0, 2p+q, 0;
and a companion triangle by adding 1 to both seed values:
p+1;
q+1, 0;
q+1, 0, -p-1;
q+1, 0, -p-q-2, 0;
q+1, 0, -p-2q-3, 0, p+1;
q+1, 0, -p-3q-4, 0, 2p+q+3, 0;
The point-by-point difference between two companions is P(n,x,p+1,q+1) - P(n,x,p,q) = S(n,x) as represented (with increasing exponents) by A053119.
Examples of such triangles are A053119 (p=q=1), A192575 (p=1, q=2),
A162514 (p=2, q=1, up to a sign factor), A192011 (p=-1, q=2), A135929 (p=-2, q=1, apart from a irregular leading T(0,0)).

Examples

			The first few rows are
-3;
2, 0;
2, 0,   3;
2, 0,   1, 0;
2, 0,  -1, 0, -3;
2, 0,  -3, 0, -4, 0;
2, 0,  -5, 0, -3, 0,  3;
2, 0,  -7, 0,  0, 0,  7, 0;
2, 0,  -9, 0,  5, 0, 10, 0,  -3;
2, 0, -11, 0, 12, 0, 10, 0, -10, 0;
2, 0, -13, 0, 21, 0,  5, 0, -20, 0, 3;
		

Crossrefs

Programs

  • Mathematica
    p = -3; q = 2; t[0, 0] = p; t[, 0] = q; t[, ?OddQ] = 0; t[n, k_] /; k > n = 0; t[n_ /; n >= 0, k_ /; k >= 0] := t[n, k] = t[n-1, k] - t[n-2, k-2]; Table[t[n, k], {n, 0, 11}, {k, 0, n}] // Flatten (* Jean-François Alcover, Nov 27 2012 *)

Formula

T(n,0) = 2 (n>0).
T(n,2) = -A060747(n-3), n>2.
T(n,4) = A028347(n-5), n>6.
T(2n,2n) = -3*(-1)^n ; T(n, 2k-1) = 0 ; T(2n+1,2n) = -(3n-2)*(-1)^n. - M. F. Hasler, Sep 28 2011

A195673 Triangle T(n,k) read by rows: T(0,0)=-2, T(1,0)=3, T(1,1)=0 and T(n,k) = T(n-1,k)-T(n-2,k-2) otherwise.

Original entry on oeis.org

-2, 3, 0, 3, 0, 2, 3, 0, -1, 0, 3, 0, -4, 0, -2, 3, 0, -7, 0, -1, 0, 3, 0, -10, 0, 3, 0, 2, 3, 0, -13, 0, 10, 0, 3, 0, 3, 0, -16, 0, 20, 0, 0, 0, -2, 3, 0, -19, 0, 33, 0, -10, 0, -5, 0, 3, 0, -22, 0, 49, 0, -30, 0, -5, 0, 2, 3, 0, -25, 0, 68
Offset: 0

Views

Author

Paul Curtz, Sep 23 2011

Keywords

Comments

Obviously T(n,k) = 0 for all odd k.
Conjecture: The polynomials p(n,x) = sum_{k=0..n} T(n,k)*x^(n-k) based on this simple recurrence for other initial constant values of T(0,0)=p and T(1,0)=q are related to the S-polynomials of A053119: p(n,x,p+1,q+1)-p(n,x,p,q) = S(n,x).

Examples

			-2;
3, 0;
3, 0,   2;
3, 0,  -1, 0;
3, 0,  -4, 0, -2;
3, 0,  -7, 0, -1, 0;
3, 0, -10, 0,  3, 0, 2;
3, 0, -13, 0, 10, 0, 3, 0.
		

Crossrefs

Cf. A195662, A192011 (p=-1, q=2), A135929 (p=-2, q=1).

A136160 Triangle T(n,k) = k*A053120(n,k).

Original entry on oeis.org

1, 0, 4, -3, 0, 12, 0, -16, 0, 32, 5, 0, -60, 0, 80, 0, 36, 0, -192, 0, 192, -7, 0, 168, 0, -560, 0, 448, 0, -64, 0, 640, 0, -1536, 0, 1024, 9, 0, -360, 0, 2160, 0, -4032, 0, 2304, 0, 100, 0, -1600, 0, 6720, 0, -10240, 0, 5120, -11, 0, 660, 0, -6160, 0, 19712, 0, -25344, 0, 11264
Offset: 1

Views

Author

Roger L. Bagula, Mar 16 2008

Keywords

Comments

The definition is equivalent to building the derivatives of the Chebyshev polynomials T(n,x) and listing the coefficients [x^k] dT/dx in row n.
Row sums are the squares A000079(n-1).
Obtained from A136265 by sign flips and nulling each second diagonal. - R. J. Mathar, Sep 04 2011

Examples

			1;
0, 4;
-3, 0, 12;
0, -16, 0, 32;
5, 0, -60, 0, 80;
0, 36, 0, -192, 0, 192;
-7, 0, 168, 0, -560, 0, 448;
0, -64, 0, 640, 0, -1536,0, 1024;
9, 0, -360, 0, 2160,0, -4032, 0, 2304;
0, 100, 0, -1600, 0, 6720, 0, -10240, 0, 5120;
-11, 0, 660, 0, -6160, 0, 19712, 0, -25344, 0, 11264;
		

References

  • Harry Hochstadt, The Functions of Mathematical Physics, Dover, New York, 1986, page 8 and pages 42 - 43

Crossrefs

Programs

  • Mathematica
    P[x, 0] = 1; P[x, 1] = x; P[x_, n_] := P[x, n] = 2*x*P[x, n - 1] - P[x, n - 2]; Q[x_, n_] := D[P[x, n + 1], x]; a = Table[CoefficientList[Q[x, n], x], {n, 0, 10}]; Flatten[a]

A138476 Triangle read by rows: expansion of (1+3*t^2)/(1-t*(2*x-t)).

Original entry on oeis.org

1, 0, 2, 2, 0, 4, 0, 2, 0, 8, -2, 0, 0, 16, 0, 6, 0, -8, 0, 32, 2, 0, -12, 0, -32, 64, 0, 10, 0, -16, 0, -96, 0, 128, -2, 0, 32, 0, 0, 0, -256, 0, 256, 0, -14, 0, 80, 0, 96, 0, -640, 0, 512
Offset: 1

Views

Author

A. Bannour (managing_office069(AT)yahoo.fr), Mar 19 2008

Keywords

Comments

See A135929 and A138034 for further information.

References

  • M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972; see Chapter 22.

Formula

G.f.: (1+3*t^2)/(1-t*(2*x-t)).

Extensions

New name from Joerg Arndt, May 15 2016

A160242 Triangle A(n,m) read by rows: a quarter of the Fourier coefficient [cos(m*t)] of the shifted Boubaker polynomial B_n(2*cos t)-2*cos(n*t).

Original entry on oeis.org

1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2
Offset: 2

Views

Author

Haydar Rahmanov, May 05 2009

Keywords

Comments

Starting from the polynomials B_n(x) defined in A137276 and A135929, we insert x=2*cos(t), and define the Fourier coefficients A(n,m) by B_n(2*cos t)-2*cos(n*t) = 4*sum(m=0,..,n-2) A(n,m)*cos(m*t).
A(n,m) is not an integer for n=0, so the table starts at n=1. Furthermore, A(n,m)=0 if n-m is odd, these regular zeros are skipped as usual, so effectively the first table entry appears at n=2.
Simpler definition from R. J. Mathar, Apr 15 2010: a(n)=1 if n =0 or n in A002061, otherwise a(n)=2. So this is a kind of characteristic function of the central polygonal numbers A002061.

Examples

			Using T^m =cos(m*t) as a notational shortcut, the expansions start
; B_1(2 cos t)-2*cos 1 t = 0
1 ; B_2(2 cos t)-2*cos 2 t = 1
0 2 ; B_3(2 cos t)-2*cos 3 t = 2*T
1 0 2 ; B_4(2 cos t)-2*cos 4 t = 1+2*T^2
0 2 0 2 ; B_5(2 cos t)-2*cos 5 t = 2*T+2*T^3
1 0 2 0 2 ; B_6(2 cos t)-2*cos 6 t = 1+2*T^2+2*T^4
0 2 0 2 0 2 ; B_7(2 cos t)-2*cos 7 t = 2*T+2*T^3+2*T^5
1 0 2 0 2 0 2 ; B_8(2 cos t)-2*cos 8 t = 1+2*T^2+2*T^4+2*T^6
0 2 0 2 0 2 0 2 ; B_9(2 cos t)-2*cos 9 t = 2*T+2*T^3+2*T^5+2*T^7
1 0 2 0 2 0 2 0 2 ; B_10(2 cos t)-2*cos 10 t = 1+2*T^2+2*T^4+2*T^6+2*T^8
0 2 0 2 0 2 0 2 0 2 ; B_11(2 cos t)-2*cos 11 t = 2*T^3+2*T^5+2*T^7+2*T^9+2*T
		

Programs

  • Mathematica
    centralPolygonalQ[n_] := Resolve[Exists[k, k>0, n == k^2-k+1], Integers];
    b[n_] := If[n == 0 || centralPolygonalQ[n], 1, 2];
    a[n_] := b[n-1];
    Table[a[n], {n, 2, 106}] (* Jean-François Alcover, Oct 31 2018, after R. J. Mathar *)

Extensions

Definition clarified, publication title corrected, sequence extended by R. J. Mathar, Dec 07 2009
Previous Showing 11-19 of 19 results.