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.

A191584 Diagonal sums of the Riordan matrix (1/(1-3*x^2),x/(1-x)) (A191582).

Original entry on oeis.org

1, 0, 4, 1, 14, 6, 47, 26, 154, 99, 496, 352, 1577, 1200, 4964, 3977, 15502, 12918, 48103, 41338, 148490, 130779, 456416, 410048, 1397905, 1276512, 4268740, 3950929, 13002638, 12170598, 39522143, 37343834, 119912698, 114209811, 363262672, 348332320, 1099015481, 1059927312
Offset: 0

Views

Author

Emanuele Munarini, Jun 07 2011

Keywords

Crossrefs

Programs

  • Mathematica
    Table[3^(Floor[n/2]+1)-Fibonacci[n+3],{n,0,100}]
    LinearRecurrence[{1,4,-3,-3},{1,0,4,1},40] (* Harvey P. Dale, Feb 23 2023 *)
  • Maxima
    makelist(3^(floor(n/2)+1)-fib(n+3),n,0,12);

Formula

a(n) = 3^(floor(n/2)+1)-fibonacci(n+3).
Recurrence: a(n+4)=a(n+3)+4*a(n+2)-3*a(n+1)-3*a(n).
G.f.: (1-x)/(1-x-4x^2+3x^3+3x^4) = (1-x)/((1-x-x^2)(1-3x^2)).

A191585 Central coefficients of the Riordan matrix (1/(1-3*x^2),x/(1-x)) (A191582).

Original entry on oeis.org

1, 1, 6, 19, 74, 276, 1056, 4047, 15606, 60382, 234356, 911802, 3554864, 13883650, 54304788, 212687199, 833958918, 3273341382, 12859792932, 50562992490, 198954466524, 783371113152, 3086377703184, 12166795814166, 47987669811276, 189361785529476
Offset: 0

Views

Author

Emanuele Munarini, Jun 07 2011

Keywords

Crossrefs

Cf. A191582.

Programs

  • Mathematica
    Table[Sum[Binomial[2n-2i-1,n-2i]3^i,{i,0,n/2}],{n,0,25}]
    CoefficientList[Series[(2-11x+12x^2+(2-9x)Sqrt[1-4x])/(2(1-4x)(2- 6x-9x^2)),{x,0,30}],x] (* Harvey P. Dale, Jun 10 2011 *)
  • Maxima
    makelist(sum(binomial(2*n-2*i-1,n-2*i)*3^i,i,0,n/2),n,0,25);

Formula

a(n) = T(2*n,n), where T(n,k) = A...(n,k).
a(n) = sum(binomial(2*n-2*i-1,n-2*i)*3^i,i=0..n/2).
G.f.: (2-11*x+12*x^2+(2-9*x)*sqrt(1-4*x))/(2*(1-4*x)*(2-6*x-9*x^2)).
Conjecture: 2*n*(n+3)*a(n) +2*(-7*n^2-19*n+24)*a(n-1) +3*(5*n^2+11*n-48)*a(n-2) +18*(n+4)*(2*n-3)*a(n-3)=0. - R. J. Mathar, Jun 14 2016
Conjecture: +4*n*a(n) +2*(-23*n+22)*a(n-1) +156*(n-2)*a(n-2) +9*(-7*n+38)*a(n-3) +162*(-2*n+5)*a(n-4)=0. - R. J. Mathar, Jun 14 2016

A279010 Alternating Jacobsthal triangle A_3(n,k) read by rows.

Original entry on oeis.org

1, 1, 1, 3, 0, 1, 3, 3, -1, 1, 9, 0, 4, -2, 1, 9, 9, -4, 6, -3, 1, 27, 0, 13, -10, 9, -4, 1, 27, 27, -13, 23, -19, 13, -5, 1, 81, 0, 40, -36, 42, -32, 18, -6, 1, 81, 81, -40, 76, -78, 74, -50, 24, -7, 1, 243, 0, 121, -116, 154, -152, 124, -74, 31, -8, 1
Offset: 0

Views

Author

N. J. A. Sloane, Dec 07 2016

Keywords

Examples

			Triangle begins:
    1;
    1,  1;
    3,  0,   1;
    3,  3,  -1,    1;
    9,  0,   4,   -2,   1;
    9,  9,  -4,    6,  -3,    1;
   27,  0,  13,  -10,   9,   -4,   1;
   27, 27, -13,   23, -19,   13,  -5,   1;
   81,  0,  40,  -36,  42,  -32,  18,  -6,  1;
   81, 81, -40,   76, -78,   74, -50,  24, -7,  1;
  243,  0, 121, -116, 154, -152, 124, -74, 31, -8, 1;
  ...
		

Crossrefs

If initial column is omitted, this is very like the Riordan matrix A191582.

Programs

  • Mathematica
    A[n_, 0] := 3^Floor[n/2];
    A[n_, k_] /; (k<0 || t>n) = 0;
    A[n_, n_] = 1;
    A[n_, k_] := A[n, k] = A[n-1, k-1] - A[n-1, k];
    Table[A[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Aug 12 2018 *)

A235501 Riordan array (1/(1-2*x^2), x/(1-x)).

Original entry on oeis.org

1, 0, 1, 2, 1, 1, 0, 3, 2, 1, 4, 3, 5, 3, 1, 0, 7, 8, 8, 4, 1, 8, 7, 15, 16, 12, 5, 1, 0, 15, 22, 31, 28, 17, 6, 1, 16, 15, 37, 53, 59, 45, 23, 7, 1, 0, 31, 52, 90, 112, 104, 68, 30, 8, 1, 32, 31, 83, 142, 202, 216, 172, 98, 38, 9, 1, 0, 63, 114, 225
Offset: 0

Views

Author

Philippe Deléham, Jan 11 2014

Keywords

Comments

Row sums are A007179(n+1).

Examples

			Triangle begins (0<=k<=n):
1
0, 1
2, 1, 1
0, 3, 2, 1
4, 3, 5, 3, 1
0, 7, 8, 8, 4, 1
8, 7, 15, 16, 12, 5, 1
0, 15, 22, 31, 28, 17, 6, 1
		

Crossrefs

Cf. Columns: A077957, A052551, A077866.
Diagonals: A000012, A001477, A022856.
Cf. Similar sequences: A059260, A191582.

Formula

T(n,n)=1, T(2n,0)=2^n, T(2n+1,0)=0, T(n,k)=T(n-1,k-1)+T(n-1,k) for 0
T(n,k)=T(n-1,k)+T(n-1,k-1)+2*T(n-2,k)-T(n-3,k)-2*T(n-3,k-1), T(0,0)=1, T(1,0)=0, T(1,1)=1, T(n,k)=0 if k<0 or if k>n.
T(n,n)=1, T(n+1,n)=n, T(n+2,n)=n*(n+1)/2 + 2.
exp(x) * e.g.f. for row n = e.g.f. for diagonal n. For example, for n = 3 we have exp(x)*(3*x + 2*x^2/2! + x^3/3!) = 3*x + 8*x^2/2! + 16*x^3/3! + 28*x^4/4! + 45*x^5/5! + .... The same property holds more generally for Riordan arrays of the form ( f(x), x/(1 - x) ). - Peter Bala, Dec 22 2014
Showing 1-4 of 4 results.