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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A156275 a(n) = 10^n*Catalan(n).

Original entry on oeis.org

1, 10, 200, 5000, 140000, 4200000, 132000000, 4290000000, 143000000000, 4862000000000, 167960000000000, 5878600000000000, 208012000000000000, 7429000000000000000, 267444000000000000000, 9694845000000000000000, 353576700000000000000000
Offset: 0

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Author

Philippe Deléham, Feb 07 2009

Keywords

Comments

In general, for m >= 1, Sum_{k>=0} 1/(m^k * Catalan(k)) = 2*m*(8*m + 1) / (4*m - 1)^2 + 24 * m^2 * arcsin(1/(2*sqrt(m))) / (4*m - 1)^(5/2). - Vaclav Kotesovec, Nov 23 2021

Crossrefs

Programs

  • Magma
    [10^n*Catalan(n): n in [0..20]]; // Vincenzo Librandi, Jul 19 2011
  • Mathematica
    Table[10^n CatalanNumber[n],{n,0,20}] (* Harvey P. Dale, Mar 12 2013 *)

Formula

a(n) = 10^n*A000108(n).
From Gary W. Adamson, Jul 18 2011: (Start)
a(n) is the upper left term in M^n, M = an infinite square production matrix:
10, 10, 0, 0, 0, ...
10, 10, 10, 0, 0, ...
10, 10, 10, 10, 0, ...
10, 10, 10, 10, 10, ...
... (End)
E.g.f.: KummerM(1/2, 2, 40*x). - Peter Luschny, Aug 26 2012
G.f.: c(10*x) with c(x) the o.g.f. of A000108 (Catalan). - Philippe Deléham, Nov 15 2013
a(n) = Sum_{k=0..n} A085880(n,k)*9^k. - Philippe Deléham, Nov 15 2013
G.f.: 1/(1 - 10*x/(1 - 10*x/(1 - 10*x/(1 - ...)))), a continued fraction. - Ilya Gutkovskiy, Aug 08 2017
Sum_{n>=0} 1/a(n) = 180/169 + 800*arctan(1/sqrt(39)) / (507*sqrt(39)). - Vaclav Kotesovec, Nov 23 2021
Sum_{n>=0} (-1)^n/a(n) = 1580/1681 - 2400*arctanh(1/sqrt(41)) / (1681*sqrt(41)). - Amiram Eldar, Jan 25 2022
D-finite with recurrence (n+1)*a(n) +20*(-2*n+1)*a(n-1)=0. - R. J. Mathar, Mar 21 2022

Extensions

a(15) corrected by Vincenzo Librandi, Jul 19 2011

A360651 Triangle T(n, m) = (n - m + 1)*C(2*n + 1, m)*C(2*n - m + 2, n - m + 1)/(2*n - m + 2).

Original entry on oeis.org

1, 3, 3, 10, 20, 10, 35, 105, 105, 35, 126, 504, 756, 504, 126, 462, 2310, 4620, 4620, 2310, 462, 1716, 10296, 25740, 34320, 25740, 10296, 1716, 6435, 45045, 135135, 225225, 225225, 135135, 45045, 6435, 24310, 194480, 680680, 1361360, 1701700, 1361360, 680680, 194480, 24310
Offset: 0

Views

Author

Vladimir Kruchinin, Feb 15 2023

Keywords

Examples

			Triangle T(n, m) starts:
[0] 1;
[1] 3,     3;
[2] 10,    20,    10;
[3] 35,    105,   105,     35;
[4] 126,   504,   756,     504,     126;
[5] 462,   2310,  4620,    4620,    2310,    462;
[6] 1716,  10296, 25740,   34320,   25740,   10296,    1716;
[7] 6435,  45045, 135135,  225225,  225225,  135135,   45045,  6435;
		

Crossrefs

Cf. A001700, A085880, A069720 (row sums).

Programs

  • Maple
    CatalanNumber := n -> binomial(2*n, n)/(n + 1):
    T := (n, k) -> (2*n + 1)*CatalanNumber(n)*binomial(n, k):
    seq(seq(T(n, k), k = 0..n), n = 0..8); # Peter Luschny, Feb 15 2023
  • Maxima
    T(n,m):=if n
    				

Formula

G.f.: 2/(1 - 4*x + sqrt(1 - 4*x - 4*x*y) - 4*x*y).
T(n, k) = binomial(n, k)*CatalanNumber(n)*(2*n + 1). - Peter Luschny, Feb 15 2023
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