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.

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A349839 Triangle T(n,k) built by placing all ones on the left edge, [1,0,0,0] repeated on the right edge, and filling the body using the Pascal recurrence T(n,k) = T(n-1,k) + T(n-1,k-1).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 3, 3, 1, 1, 1, 4, 6, 4, 2, 0, 1, 5, 10, 10, 6, 2, 0, 1, 6, 15, 20, 16, 8, 2, 0, 1, 7, 21, 35, 36, 24, 10, 2, 1, 1, 8, 28, 56, 71, 60, 34, 12, 3, 0, 1, 9, 36, 84, 127, 131, 94, 46, 15, 3, 0, 1, 10, 45, 120, 211, 258, 225, 140, 61, 18, 3, 0, 1, 11, 55, 165, 331, 469, 483, 365, 201, 79, 21, 3, 1
Offset: 0

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Author

Michael A. Allen, Dec 01 2021

Keywords

Comments

This is the m=4 member in the sequence of triangles A007318, A059259, A118923, A349839, A349841 which have all ones on the left side, ones separated by m-1 zeros on the other side, and whose interiors obey Pascal's recurrence.
T(n,k) is the (n,n-k)-th entry of the (1/(1-x^4),x/(1-x)) Riordan array.
For n>0, T(n,n-1) = A008621(n-1).
For n>1, T(n,n-2) = A001972(n-2).
For n>2, T(n,n-3) = A122046(n).
Sums of rows give A115451.
Sums of antidiagonals give A349840.

Examples

			Triangle begins:
  1;
  1,   0;
  1,   1,   0;
  1,   2,   1,   0;
  1,   3,   3,   1,   1;
  1,   4,   6,   4,   2,   0;
  1,   5,  10,  10,   6,   2,   0;
  1,   6,  15,  20,  16,   8,   2,   0;
  1,   7,  21,  35,  36,  24,  10,   2,   1;
  1,   8,  28,  56,  71,  60,  34,  12,   3,   0;
  1,   9,  36,  84, 127, 131,  94,  46,  15,   3,   0;
  1,  10,  45, 120, 211, 258, 225, 140,  61,  18,   3,   0;
  1,  11,  55, 165, 331, 469, 483, 365, 201,  79,  21,   3,   1;
		

Crossrefs

Other members of sequence of triangles: A007318, A059259, A118923, A349841.

Programs

  • Mathematica
    Flatten[Table[CoefficientList[Series[(1-x*y)/((1-(x*y)^4)(1 - x - x*y)), {x, 0, 24}, {y, 0, 12}], {x, y}][[n+1,k+1]],{n,0,12},{k,0,n}]]

Formula

G.f.: (1-x*y)/((1-(x*y)^4)(1-x-x*y)) in the sense that T(n,k) is the coefficient of x^n*y^k in the series expansion of the g.f.
T(n,0) = 1.
T(n,n) = delta(n mod 4,0).
T(n,1) = n-1 for n>0.
T(n,2) = (n-1)*(n-2)/2 for n>1.
T(n,3) = (n-1)*(n-2)*(n-3)/6 for n>2.
T(n,4) = C(n-1,4) + 1 for n>3.
T(n,5) = C(n-1,5) + n - 5 for n>4.
For 0 <= k < n, T(n,k) = (n-k)*Sum_{j=0..floor(k/4)} binomial(n-4*j,n-k)/(n-4*j).
The g.f. of the n-th subdiagonal is 1/((1-x^4)(1-x)^n).

A030441 Values of Newton-Gregory forward interpolating polynomial (1/3)*(2*n - 3)*(2*n^2 - 3*n + 4).

Original entry on oeis.org

-4, -1, 2, 13, 40, 91, 174, 297, 468, 695, 986, 1349, 1792, 2323, 2950, 3681, 4524, 5487, 6578, 7805, 9176, 10699, 12382, 14233, 16260, 18471, 20874, 23477, 26288, 29315, 32566, 36049, 39772, 43743, 47970, 52461, 57224, 62267, 67598, 73225, 79156, 85399
Offset: 0

Views

Author

Ilias.Kotsireas(AT)lip6.fr (Ilias Kotsireas)

Keywords

Crossrefs

Equals A030434 shifted left twice.

Programs

  • Mathematica
    LinearRecurrence[{4,-6,4,-1},{-4,-1,2,13},50] (* Harvey P. Dale, Apr 20 2015 *)
  • PARI
    a(n) = (1/3)*(2*n-3)*(2*n^2-3*n+4); \\ Michel Marcus, May 18 2014

Formula

a(n) - A177342(n-1) = (n-1)^2, with n>1. For n=6, a(6) - A177342(5) = 174 - 149 = 5^2. - Bruno Berselli, May 23 2010
a(n) = 4*a(n-1)-6*a(n-2)+4*a(n-3)-a(n-4). - Colin Barker, May 18 2014
G.f.: (15*x^3-18*x^2+15*x-4) / (x-1)^4. - Colin Barker, May 18 2014
a(n) = A059259(2*n,3), n>1. - Mathew Englander, May 17 2014

A030442 Values of Newton-Gregory forward interpolating polynomial (1/6)*(4*n^4 - 60*n^3 + 347*n^2 - 927*n + 978).

Original entry on oeis.org

163, 57, 16, 4, 1, 3, 22, 86, 239, 541, 1068, 1912, 3181, 4999, 7506, 10858, 15227, 20801, 27784, 36396, 46873, 59467, 74446, 92094, 112711, 136613, 164132, 195616, 231429, 271951, 317578, 368722, 425811, 489289, 559616, 637268, 722737, 816531, 919174
Offset: 0

Views

Author

Ilias.Kotsireas(AT)lip6.fr (Ilias Kotsireas), Dec 11 1999

Keywords

Crossrefs

Cf. A059259.

Programs

  • Maple
    A030442:=n->(1/6)*(4*n^4-60*n^3+347*n^2-927*n+978); seq(A030442(n), n=0..40); # Wesley Ivan Hurt, May 19 2014
  • Mathematica
    Table[(1/6)*(4*n^4 - 60*n^3 + 347*n^2 - 927*n + 978), {n, 0, 40}] (* Wesley Ivan Hurt, May 19 2014 *)
  • PARI
    a(n) = (1/6)*(4*n^4-60*n^3+347*n^2-927*n+978); \\ Michel Marcus, May 18 2014

Formula

a(n) = 5*a(n-1)-10*a(n-2)+10*a(n-3)-5*a(n-4)+a(n-5). - Colin Barker, May 18 2014
G.f.: -(386*x^4-1136*x^3+1361*x^2-758*x+163) / (x-1)^5. - Colin Barker, May 18 2014
a(n) = A059259(2*n-5,4), n>4. - Mathew Englander, May 18 2014
E.g.f.: exp(x)*(978 - 636*x + 195*x^2 - 36*x^3 + 4*x^4)/6. - Stefano Spezia, Sep 11 2022

A180153 a(n) = 10*a(n-1) + A109242(n).

Original entry on oeis.org

1, 121, 12421, 1246421, 124696421, 12470296421, 1247037296421, 124703817296421, 12470382717296421, 1247038282717296421, 124703828392717296421, 12470382840592717296421, 1247038284073592717296421, 124703828407513592717296421, 12470382840753013592717296421
Offset: 1

Views

Author

Mark Dols, Aug 13 2010

Keywords

Crossrefs

Programs

  • PARI
    Vec(x / ((x-1)*(10*x-1)^2*(100*x-1)) + O(x^30)) \\ Colin Barker, Oct 03 2015

Formula

From Colin Barker, Oct 03 2015: (Start)
a(n) = 121*a(n-1)-2220*a(n-2)+12100*a(n-3)-10000*a(n-4) for n>4.
G.f.: x / ((x-1)*(10*x-1)^2*(100*x-1)).
(End)
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