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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A060539 Table by antidiagonals of number of ways of choosing k items from n*k.

Original entry on oeis.org

1, 1, 2, 1, 6, 3, 1, 20, 15, 4, 1, 70, 84, 28, 5, 1, 252, 495, 220, 45, 6, 1, 924, 3003, 1820, 455, 66, 7, 1, 3432, 18564, 15504, 4845, 816, 91, 8, 1, 12870, 116280, 134596, 53130, 10626, 1330, 120, 9, 1, 48620, 735471, 1184040, 593775, 142506, 20475, 2024, 153, 10
Offset: 1

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Author

Henry Bottomley, Apr 02 2001

Keywords

Examples

			Square array A(n,k) begins:
  1,  1,    1,     1,      1,       1,        1, ...
  2,  6,   20,    70,    252,     924,     3432, ...
  3, 15,   84,   495,   3003,   18564,   116280, ...
  4, 28,  220,  1820,  15504,  134596,  1184040, ...
  5, 45,  455,  4845,  53130,  593775,  6724520, ...
  6, 66,  816, 10626, 142506, 1947792, 26978328, ...
  7, 91, 1330, 20475, 324632, 5245786, 85900584, ...
		

Crossrefs

Columns include A000027, A000384, A006566, A060541.
Main diagonal is A014062.
Cf. A295772.

Programs

  • Maple
    A:= (n, k)-> binomial(n*k, k):
    seq(seq(A(n, 1+d-n), n=1..d), d=1..10);  # Alois P. Heinz, Jul 28 2023
  • PARI
    { i=0; for (m=1, 20, for (n=1, m, k=m - n + 1; write("b060539.txt", i++, " ", binomial(n*k, k))); ) } \\ Harry J. Smith, Jul 06 2009

Formula

A(n,k) = binomial(n*k,k) = A007318(n*k,k) = A060538(n,k)/A060538(n-1,k).

A295773 a(n) = Sum_{k=0..n} binomial(k^2, k).

Original entry on oeis.org

1, 2, 8, 92, 1912, 55042, 2002834, 87903418, 4514068786, 265401903136, 17575711359576, 1294325676386112, 104913619501093500, 9281271920245432932, 889811788303594625412, 91895379599481072720852, 10170646981621794947354052, 1200909691326112843842751962
Offset: 0

Views

Author

Vaclav Kotesovec, Nov 27 2017

Keywords

Crossrefs

Programs

  • Magma
    [&+[Binomial(k^2, k): k in [0..n]]: n in [0..20]]; // Vincenzo Librandi, Jan 10 2019
  • Mathematica
    Table[Sum[Binomial[k^2, k], {k, 0, n}], {n, 0, 20}]
  • PARI
    a(n) = sum(k=0, n, binomial(k^2, k)); \\ Michel Marcus, Jan 10 2019
    

Formula

a(n) ~ exp(n - 1/2) * n^(n - 1/2) / sqrt(2*Pi).
Showing 1-2 of 2 results.