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 1-2 of 2 results.

A316674 Number A(n,k) of paths from {0}^k to {n}^k that always move closer to {n}^k; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 3, 2, 1, 1, 13, 26, 4, 1, 1, 75, 818, 252, 8, 1, 1, 541, 47834, 64324, 2568, 16, 1, 1, 4683, 4488722, 42725052, 5592968, 26928, 32, 1, 1, 47293, 617364026, 58555826884, 44418808968, 515092048, 287648, 64, 1
Offset: 0

Views

Author

Alois P. Heinz, Jul 10 2018

Keywords

Comments

A(n,k) is the number of nonnegative integer matrices with k columns and any number of nonzero rows with column sums n. - Andrew Howroyd, Jan 23 2020

Examples

			Square array A(n,k) begins:
  1,  1,     1,         1,              1,                    1, ...
  1,  1,     3,        13,             75,                  541, ...
  1,  2,    26,       818,          47834,              4488722, ...
  1,  4,   252,     64324,       42725052,          58555826884, ...
  1,  8,  2568,   5592968,    44418808968,      936239675880968, ...
  1, 16, 26928, 515092048, 50363651248560, 16811849850663255376, ...
		

Crossrefs

Columns k=0..3 give: A000012, A011782, A052141, A316673.
Rows n=0..2 give: A000012, A000670, A059516.
Main diagonal gives A316677.

Programs

  • Maple
    A:= (n, k)-> `if`(k=0, 1, ceil(2^(n-1))*add(add((-1)^i*
         binomial(j, i)*binomial(j-i, n)^k, i=0..j), j=0..k*n)):
    seq(seq(A(n, d-n), n=0..d), d=0..10);
  • Mathematica
    A[n_, k_] := Sum[If[k == 0, 1, Binomial[j+n-1, n]^k] Sum[(-1)^(i-j)* Binomial[i, j], {i, j, n k}], {j, 0, n k}];
    Table[Table[A[n, d-n], {n, 0, d}], {d, 0, 10}] // Flatten (* Jean-François Alcover, Nov 04 2021 *)
  • PARI
    T(n,k)={my(m=n*k); sum(j=0, m, binomial(j+n-1,n)^k*sum(i=j, m, (-1)^(i-j)*binomial(i, j)))} \\ Andrew Howroyd, Jan 23 2020

Formula

A(n,k) = A262809(n,k) * A011782(n) for k>0, A(n,0) = 1.
A(n,k) = Sum_{j=0..n*k} binomial(j+n-1,n)^k * Sum_{i=j..n*k} (-1)^(i-j) * binomial(i,j). - Andrew Howroyd, Jan 23 2020

A262810 Number of lattice paths from {n}^n to {0}^n using steps that decrement one or more components by one.

Original entry on oeis.org

1, 1, 13, 16081, 5552351121, 1050740615666453461, 179349571255187154941191217629, 41020870889694863957061607086939138327565057, 17469051230066445323872793284679234619523576313653708533767425
Offset: 0

Views

Author

Alois P. Heinz, Oct 02 2015

Keywords

Examples

			a(2) = 13: [(2,2),(1,2),(0,2),(0,1),(0,0)], [(2,2),(1,2),(0,1),(0,0)], [(2,2),(1,2),(1,1),(0,1),(0,0)], [(2,2),(1,2),(1,1),(0,0)], [(2,2),(1,2),(1,1),(1,0),(0,0)], [(2,2),(2,1),(1,1),(0,1),(0,0)], [(2,2),(2,1),(1,1),(0,0)], [(2,2),(2,1),(1,1),(1,0),(0,0)], [(2,2),(2,1),(2,0),(0,1),(0,0)], [(2,2),(2,1),(1,0),(0,0)], [(2,2),(1,1),(0,1),(0,0)], [(2,2),(1,1),(0,0)], [(2,2),(1,1),(1,0),(0,0)].
		

Crossrefs

Main diagonal of A262809.
Cf. A316677.

Programs

  • Mathematica
    Flatten[{1, Table[Sum[Sum[(-1)^i*Binomial[j, i]*Binomial[j - i, n]^n, {i, 0, j}], {j, 0, n^2}], {n, 1, 10}]}] (* Vaclav Kotesovec, Mar 23 2016 *)
  • PARI
    a(n)=sum(j=0,n^2,sum(i=0,j, (-1)^i*binomial(j, i)*binomial(j - i, n)^n)) \\ Charles R Greathouse IV, Jul 29 2016

Formula

a(n) = A262809(n,n).
a(n) ~ n^(n^2 - n/2 + 1) / (exp(1/12) * 2^(n + log(2)/24) * Pi^((n-1)/2) * log(2)^(n^2+1)). - Vaclav Kotesovec, Mar 23 2016
Showing 1-2 of 2 results.