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 1-5 of 5 results.

A099511 Row sums of triangle A099510, so that a(n) = Sum_{k=0..n} coefficient of z^k in (1 + 2*z + z^2)^(n-[k/2]), where [k/2] is the integer floor of k/2.

Original entry on oeis.org

1, 3, 6, 17, 45, 116, 305, 799, 2090, 5473, 14329, 37512, 98209, 257115, 673134, 1762289, 4613733, 12078908, 31622993, 82790071, 216747218, 567451585, 1485607537, 3889371024, 10182505537, 26658145587, 69791931222, 182717648081
Offset: 0

Views

Author

Paul D. Hanna, Oct 21 2004

Keywords

Crossrefs

Cf. A099510.

Programs

  • PARI
    a(n)=sum(k=0,n,polcoeff((1+2*x+x^2+x*O(x^k))^(n-k\2),k))

Formula

G.f.: (1+x-x^2)/(1-2*x-x^2-2*x^3+x^4). a(n) = Sum_{k=0..n} binomial(2*n-2*[k/2], k).

A099509 Triangle, read by rows, of trinomial coefficients arranged so that there are n+1 terms in row n by setting T(n,k) equal to the coefficient of z^k in (1 + z + z^2)^(n-[k/2]), for n>=k>=0, where [k/2] is the integer floor of k/2.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 3, 2, 1, 4, 6, 7, 1, 1, 5, 10, 16, 6, 3, 1, 6, 15, 30, 19, 16, 1, 1, 7, 21, 50, 45, 51, 10, 4, 1, 8, 28, 77, 90, 126, 45, 30, 1, 1, 9, 36, 112, 161, 266, 141, 126, 15, 5, 1, 10, 45, 156, 266, 504, 357, 393, 90, 50, 1, 1, 11, 55, 210, 414, 882, 784, 1016, 357
Offset: 0

Views

Author

Paul D. Hanna, Oct 20 2004

Keywords

Comments

Row sums form absolute values of A078039. In general if T(n,k) = coefficient of z^k in (a + b*z + c*z^2)^(n-[k/2]), then the resulting number triangle will have the o.g.f.: ((1-a*x-c*x^2*y^2) + b*x*y)/((1-a*x-c*x^2*y^2)^2 - x*(b*x*y)^2).

Examples

			Rows begin:
[1],
[1,1],
[1,2,1],
[1,3,3,2],
[1,4,6,7,1],
[1,5,10,16,6,3],
[1,6,15,30,19,16,1],
[1,7,21,50,45,51,10,4],
[1,8,28,77,90,126,45,30,1],
[1,9,36,112,161,266,141,126,15,5],...
and can be derived from coefficients of (1+z+z^2)^n:
[1],
[1,1,1],
[1,2,3,2,1],
[1,3,6,7,6,3,1],
[1,4,10,16,19,16,10,4,1],
[1,5,15,30,45,51,45,30,15,5,1],...
by shifting each column k down by [k/2] rows.
		

Crossrefs

Programs

  • PARI
    T(n,k)=if(n
    				

Formula

G.f.: (1-x+x*y-x^2*y^2)/((1-x)^2-2*x^2*y^2+x^3*y^2+x^4*y^4).

A099512 Triangle, read by rows, of trinomial coefficients arranged so that there are n+1 terms in row n by setting T(n,k) equal to the coefficient of z^k in (1 + 3*z + z^2)^(n-[k/2]), for n>=k>=0, where [k/2] is the integer floor of k/2.

Original entry on oeis.org

1, 1, 3, 1, 6, 1, 1, 9, 11, 6, 1, 12, 30, 45, 1, 1, 15, 58, 144, 30, 9, 1, 18, 95, 330, 195, 144, 1, 1, 21, 141, 630, 685, 873, 58, 12, 1, 24, 196, 1071, 1770, 3258, 685, 330, 1, 1, 27, 260, 1680, 3801, 9198, 3989, 3258, 95, 15, 1, 30, 333, 2484, 7210, 21672, 15533
Offset: 0

Views

Author

Paul D. Hanna, Oct 20 2004

Keywords

Comments

Row sums form A099513. In general if T(n,k) = coefficient of z^k in (a + b*z + c*z^2)^(n-[k/2]), then the resulting number triangle will have the o.g.f.: ((1-a*x-c*x^2*y^2) + b*x*y)/((1-a*x-c*x^2*y^2)^2 - x*(b*x*y)^2).

Examples

			Rows begin:
[1],
[1,3],
[1,6,1],
[1,9,11,6],
[1,12,30,45,1],
[1,15,58,144,30,9],
[1,18,95,330,195,144,1],
[1,21,141,630,685,873,58,12],
[1,24,196,1071,1770,3258,685,330,1],
[1,27,260,1680,3801,9198,3989,3258,95,15],...
and can be derived from coefficients of (1+3*z+z^2)^n:
[1],
[1,3,1],
[1,6,11,6,1],
[1,9,30,45,30,9,1],
[1,12,58,144,195,144,58,12,1],
[1,15,95,330,685,873,685,330,95,15,1],...
by shifting each column k down by [k/2] rows.
		

Crossrefs

Programs

  • PARI
    T(n,k)=if(n
    				

Formula

G.f.: (1-x+3*x*y-x^2*y^2)/((1-x)^2-2*x^2*y^2-7*x^3*y^2+x^4*y^4).

A099514 Triangle, read by rows, of trinomial coefficients arranged so that there are n+1 terms in row n by setting T(n,k) equal to the coefficient of z^k in (1 + z + 2*z^2)^(n-[k/2]), for n>=k>=0, where [k/2] is the integer floor of k/2.

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 1, 3, 5, 4, 1, 4, 9, 13, 4, 1, 5, 14, 28, 18, 12, 1, 6, 20, 50, 49, 56, 8, 1, 7, 27, 80, 105, 161, 56, 32, 1, 8, 35, 119, 195, 366, 210, 200, 16, 1, 9, 44, 168, 329, 721, 581, 732, 160, 80, 1, 10, 54, 228, 518, 1288, 1337, 2045, 780, 640, 32, 1, 11, 65, 300, 774, 2142, 2716, 4824, 2674, 2884, 432, 192
Offset: 0

Views

Author

Paul D. Hanna, Oct 20 2004

Keywords

Comments

Row sums form A099515. In general if T(n,k) = coefficient of z^k in (a + b*z + c*z^2)^(n-[k/2]), then the resulting number triangle will have the o.g.f.: ((1-a*x-c*x^2*y^2) + b*x*y)/((1-a*x-c*x^2*y^2)^2 - x*(b*x*y)^2).

Examples

			Rows begin:
[1],
[1,1],
[1,2,2],
[1,3,5,4],
[1,4,9,13,4],
[1,5,14,28,18,12],
[1,6,20,50,49,56,8],
[1,7,27,80,105,161,56,32],
[1,8,35,119,195,366,210,200,16],
[1,9,44,168,329,721,581,732,160,80],...
and can be derived from coefficients of (1+z+2*z^2)^n:
[1],
[1,1,2],
[1,2,5,4,4],
[1,3,9,13,18,12,8],
[1,4,14,28,49,56,56,32,16],
[1,5,20,50,105,161,210,200,160,80,32],...
by shifting each column k down by [k/2] rows.
		

Crossrefs

Programs

  • Mathematica
    With[{m = 11}, CoefficientList[CoefficientList[Series[(1-x+x*y-2*x^2*y^2)/ ((1-x)^2-4*x^2*y^2+3*x^3*y^2+4*x^4*y^4), {x, 0 , m}, {y, 0, m}], x], y]] // Flatten (* Georg Fischer, Feb 17 2020 *)
  • PARI
    T(n,k)=if(n
    				

Formula

G.f.: (1-x+x*y-2*x^2*y^2)/((1-x)^2-4*x^2*y^2+3*x^3*y^2+4*x^4*y^4).

Extensions

a(50..51) corrected by Georg Fischer, Feb 17 2020

A099527 Triangle, read by rows, of trinomial coefficients arranged so that there are n+1 terms in row n by setting T(n,k) equal to the coefficient of z^k in (2 + 3*z + z^2)^(n-[k/2]), for n>=k>=0, where [k/2] is the integer floor of k/2.

Original entry on oeis.org

1, 2, 3, 4, 12, 1, 8, 36, 13, 6, 16, 96, 66, 63, 1, 32, 240, 248, 360, 33, 9, 64, 576, 800, 1560, 321, 180, 1, 128, 1344, 2352, 5760, 1970, 1683, 62, 12, 256, 3072, 6496, 19152, 9420, 10836, 985, 390, 1, 512, 6912, 17152, 59136, 38472, 55692, 8989, 5418, 100, 15
Offset: 0

Views

Author

Paul D. Hanna, Oct 20 2004

Keywords

Comments

Row sums form A099528. In general if T(n,k) = coefficient of z^k in (a + b*z + c*z^2)^(n-[k/2]), then the resulting number triangle will have the o.g.f.: ((1-a*x-c*x^2*y^2) + b*x*y)/((1-a*x-c*x^2*y^2)^2 - x*(b*x*y)^2).

Examples

			Rows begin:
[1],
[2,3],
[4,12,1],
[8,36,13,6],
[16,96,66,63,1],
[32,240,248,360,33,9],
[64,576,800,1560,321,180,1],
[128,1344,2352,5760,1970,1683,62,12],
[256,3072,6496,19152,9420,10836,985,390,1],
[512,6912,17152,59136,38472,55692,8989,5418,100,15],...
and can be derived from the coefficients of (2+3*z+z^2)^n:
[1],
[2,3,1],
[4,12,13,6,1],
[8,36,66,63,33,9,1],
[16,96,248,360,321,180,62,12,1],
[32,240,800,1560,1970,1683,985,390,100,15,1],...
by shifting each column k down by [k/2] rows.
		

Crossrefs

Programs

  • PARI
    T(n,k)=if(n
    				

Formula

G.f.: (1-x*(2-3*y)-x^2*y^2)/(1-4*x+x^2*(4-2*y^2)-5*x^3*y^2+x^4*y^4).
Showing 1-5 of 5 results.