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 21-24 of 24 results.

A317403 a(n)=(-1)^((n-2)*(n-1)/2)*2^(n-1)*n^(n-3).

Original entry on oeis.org

1, 1, -4, -32, 400, 6912, -153664, -4194304, 136048896, 5120000000, -219503494144, -10567230160896, 564668382613504, 33174037869887488, -2125764000000000000, -147573952589676412928, 11034809241396899282944, 884295678882933431599104, -75613185918270483380568064
Offset: 1

Views

Author

Rigoberto Florez, Aug 26 2018

Keywords

Comments

Discriminant of Fibonacci polynomials.
Fibonacci polynomials are defined as F(0)=0, F(1)=1 and F(n)=x*F(n-1)+F(n-2) for n>1. Coefficients are given in triangle A168561 with offset 1.

Crossrefs

Programs

  • Magma
    [(-1)^((n-2)*(n-1) div 2)*2^(n-1)*n^(n-3): n in [1..20]]; // Vincenzo Librandi, Aug 27 2018
  • Mathematica
    Array[(-1)^((#-2)*(#-1)/2)*2^(#-1)*#^(#-3)&,20]
  • PARI
    concat([1], [poldisc(p) | p<-Vec(x/(1-x^2-y*x) - x + O(x^20))]) \\ Andrew Howroyd, Aug 26 2018
    

A172249 Triangle, read by rows, given by [0,1/3,-1/3,0,0,0,0,0,0,0,...] DELTA [3,-1/3,1/3,0,0,0,0,0,0,0,...] where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 0, 3, 0, 1, 8, 0, 0, 6, 21, 0, 0, 1, 25, 55, 0, 0, 0, 9, 90, 144, 0, 0, 0, 1, 51, 300, 377, 0, 0, 0, 0, 12, 234, 954, 987, 0, 0, 0, 0, 1, 86, 951, 2939, 2584, 0, 0, 0, 0, 0, 15, 480, 3573, 8850, 6765, 0, 0, 0, 0, 0, 1, 130, 2305, 12707, 26195, 17711, 0, 0, 0, 0, 0, 0, 18, 855
Offset: 0

Views

Author

Philippe Deléham, Jan 29 2010

Keywords

Comments

Diagonal sums : |A077897|. Column sums : A001353 .

Examples

			Triangle begins :
1,
0,3,
0,1,8,
0,0,6,21,
0,0,1,25,55,
0,0,0,9,90,144,
0,0,0,1,51,300,377,
0,0,0,0,12,234,954,987,
0,0,0,0,1,86,951,2939,2584,
0,0,0,0,0,15,480,3573,8850,6765,
0,0,0,0,0,1,130,2305,12707,26195,17711,
		

Crossrefs

Programs

  • Maxima
    T(n,k):=2*sum((j*binomial(n+j,2*n-2*k+2*j)*binomial(n-k+j,j))/(n+j),j,1,n+k); /* Vladimir Kruchinin_, Oct 28 2020 */

Formula

T(n,k) = 3*T(n-1,k-1) + T(n-2,k-1) - T(n-2,k-2), T(0,0)=1, T(n,k) = 0 if k>n or if k<0.
Sum_{k, 0<=k<=n} T(n,k)= 3^n = A000244(n) (row sums).
G.f.: 1/(1-3*x*y-x^2*y+x^2*y^2). - R. J. Mathar, Aug 11 2015
T(n,k) = 2*Sum_{j=1..n+k} j*C(n+j,2*n-2*k+2*j)*C(n-k+j,j)/(n+j), T(0,0)=1. - Vladimir Kruchinin, Oct 28 2020

A286986 Number of connected dominating sets in the n-antiprism graph.

Original entry on oeis.org

3, 15, 54, 175, 543, 1642, 4875, 14271, 41310, 118487, 337263, 953810, 2682579, 7508655, 20929158, 58121407, 160877055, 443993146, 1222110555, 3355879647, 9195143598, 25144855655, 68635721679, 187035899810, 508896450723, 1382653280847, 3751638404310
Offset: 1

Views

Author

Eric W. Weisstein, May 17 2017

Keywords

Programs

  • Mathematica
    Table[6 n ChebyshevU[n - 1, 3/2] + (1 - 2 n) LucasL[2 n], {n, 30}] (* Eric W. Weisstein, May 17 2017 *)
    LinearRecurrence[{6, -11, 6, -1}, {3, 15, 54, 175}, 30] (* Eric W. Weisstein, May 17 2017 *)
    Rest[CoefficientList[Series[(3*x - 3*x^2 - 3*x^3 - 2*x^4)/(1 - 6*x + 11*x^2 - 6*x^3 + x^4), {x,0,50}], x]] (* G. C. Greubel, May 17 2017 *)
  • PARI
    x='x+O('x^50); Vec((3*x - 3*x^2 - 3*x^3 - 2*x^4)/(1 - 6*x + 11*x^2 - 6*x^3 + x^4)) \\ G. C. Greubel, May 17 2017

Formula

From G. C. Greubel, May 17 2017: (Start)
a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3) - a(n-4).
G.f.: (3 - 3*x - 3*x^2 - 2*x^3)*x/(1 - 6*x + 11*x^2 - 6*x^3 + x^4). (End)
a(n) = 28*A001871(n) -72*A001871(n-1) -15*A001906(n)-26*A001906(n+1). - R. J. Mathar, Dec 16 2024

A317450 a(n)=(-1)^((n-2)*(n-1)/2)*2^((n-1)^2)*n^(n-3).

Original entry on oeis.org

1, 1, -16, -2048, 1638400, 7247757312, -164995463643136, -18446744073709551616, 9803356117276277820358656, 24178516392292583494123520000000, -271732164163901599116133024293512544256, -13717048991958695477963985711266803110069141504, 3074347100178259797134292590832254504315406543889629184
Offset: 1

Views

Author

Rigoberto Florez, Aug 26 2018

Keywords

Comments

Discriminant of Pell polynomials.
Pell polynomials are defined as P(0)=0, P(1)=1 and P(n)=2xP(n-1)+P(n-2) for n>1.

Crossrefs

Programs

  • Mathematica
    Array[(-1)^((#-2)*(#-1)/2)* 2^((#-1)^2)*#^(#-3)&,15]
Previous Showing 21-24 of 24 results.