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.

A101494 Triangle, read by rows, where T(n,k) = Sum_{j=0..n-k-1} C(j+k,j)*T(n-1,j+k) for n>k>=0 with T(n,n)=1.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 4, 3, 1, 1, 9, 8, 4, 1, 1, 23, 23, 13, 5, 1, 1, 66, 73, 44, 19, 6, 1, 1, 210, 253, 162, 73, 26, 7, 1, 1, 733, 948, 643, 302, 111, 34, 8, 1, 1, 2781, 3817, 2724, 1337, 506, 159, 43, 9, 1, 1, 11378, 16433, 12259, 6266, 2457, 788, 218, 53, 10, 1, 1, 49864, 75295
Offset: 0

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Author

Paul D. Hanna, Jan 21 2005

Keywords

Comments

Column 0 equals row sums (A026898) shift right.
T(n,k) is the number of m-tuples of nonnegative integers satisfying these two criteria: (i) there are exactly k 0’s, and (ii) the remaining m-k elements are positive integers less than or equal to n-m. - Mathew Englander, Feb 25 2021

Examples

			4th row sum = 23 = (5-0)^0+(5-1)^1+(5-2)^2+(5-3)^3+(5-4)^4.
5th row sum = 66 = (6-0)^0+(6-1)^1+(6-2)^2+(6-3)^3+(6-4)^4+(6-5)^5.
T(6,0) = 66 = 1*23 + 1*23 + 1*13 + 1*5 + 1*1 + 1*1.
T(6,1) = 73 = 1*23 + 2*13 + 3*5 + 4*1 + 5*1.
T(6,2) = 44 = 1*13 + 3*5 + 6*1 + 10*1.
Rows begin:
1;
1, 1;
2, 1, 1;
4, 3, 1, 1;
9, 8, 4, 1, 1;
23, 23, 13, 5, 1, 1;
66, 73, 44, 19, 6, 1, 1;
210, 253, 162, 73, 26, 7, 1, 1;
733, 948, 643, 302, 111, 34, 8, 1, 1;
2781, 3817, 2724, 1337, 506, 159, 43, 9, 1, 1;
11378, 16433, 12259, 6266, 2457, 788, 218, 53, 10, 1, 1;
49864, 75295, 58423, 30953, 12558, 4147, 1163, 289, 64, 11, 1, 1;
232769, 365600, 293902, 160823, 67259, 22878, 6574, 1647, 373, 76, 12, 1, 1; ...
		

Crossrefs

Cf. A101495, A026898, A089246 (first differences by column), A304357 (antidiagonal sums, empirically), A034856 (fourth diagonal).

Programs

  • GAP
    Flat(List([0..10],n->List([0..n],k->Sum([0..n-k],j->Binomial(j+k,j)*(n-k-j)^j)))); # Muniru A Asiru, Mar 07 2019
  • PARI
    T(n,k)=if(n
    				
  • PARI
    T(n,k)=polcoeff(sum(m=0,n-k, x^m/(1-m*x +x*O(x^(n-k)))^(k+1)),n-k)
    for(n=0,12,for(k=0,n,print1(T(n,k),", "));print()) \\ Paul D. Hanna, Mar 06 2013
    

Formula

T(n,0) = A026898(n-1).
T(n,k) = Sum_{j=0..n-k} binomial(j+k,j)*(n-k-j)^j. - Vladeta Jovovic, Sep 07 2006
G.f.: A(x,y) = Sum_{n>=0} Sum_{k>=0} x^(n+k)*y^k / (1 - n*x)^(k+1). - Paul D. Hanna, Mar 06 2013
From Mathew Englander, Feb 25 2021: (Start)
G.f. of row n: Sum_{i=0..n} (x+n-i)^i.
T(n,k) = Sum_{j=k..n} A089246(j,k).
Antidiagonal sums: Sum_{j = 0..n} Sum_{i = j..floor((n+j)/2)} binomial(i,j)*(n+j-2*i)^j. (End)