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 1-3 of 3 results.

A067298 Generalized Catalan triangle, based on C(2,2; n) = A064340(n).

Original entry on oeis.org

1, 1, 2, 4, 5, 9, 28, 32, 36, 64, 256, 284, 300, 328, 584, 2704, 2960, 3072, 3184, 3440, 6144, 31168, 33872, 34896, 35680, 36704, 39408, 70576, 380608, 411776, 422592, 429760, 436928, 447744, 478912, 859520, 4840960, 5221568, 5346240, 5421952, 5487488, 5563200, 5687872, 6068480, 10909440
Offset: 0

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Author

Wolfdieter Lang, Feb 05 2002

Keywords

Comments

For corresponding Catalan triangle with C(1,1; n) = A000108(n) see A028364.
Identity for each row n>=1: T(n, m) + T(n, n-(m+1)) = T(n, n) = A067297(n) for m=0..floor((n-1)/2). E.g., T(2*k+1, k) = A067297(2*k+1)/2.

Examples

			Triangle begins:
    1;
    1,   2;
    4,   5,   9;
   28,  32,  36,  64;
  256, 284, 300, 328, 584;
  ...
		

Crossrefs

The columns (without leading zeros) give for m=0..3: A064340, A067299, 3*A067300, 8*A067301.
The main diagonal gives A067297. The row sums give A067302.

Programs

  • PARI
    A064340(n) = if(n>1, sum(m=0, n-2, (m+1)*(m+2)*binomial(2*(n-2)-m, n-2-m)/2^(m+1))*(4^(n-1))/(n-1), 1);
    T(n, m) = sum(i=0, m, A064340(i)*A064340(n-i)); \\ Jinyuan Wang, Apr 20 2025

Formula

T(n, m) = Sum_{i=0..m} C(2,2; i)*C(2,2; n-i) if n >= m >= 0 else 0.
G.f. for column m (without leading zeros): (c(m, x)*c(2,2; x)-c2(m-1, x))/x^m, with c(2,2; x) = (1-3*x*c(4*x))/(1-2*x*c(4*x))^2 (g.f. for C(2,2; n)), c(x) = g.f. for Catalan numbers A000108, c(m, x) = Sum_{n=0..m} C(2,2; n)*x^n and c2(m, x) = Sum_{n=0..m} A067297(n)*x^n for m=0, 1, 2, ...

Extensions

More terms from Jinyuan Wang, Apr 20 2025

A067299 Second column of triangle A067298.

Original entry on oeis.org

2, 5, 32, 284, 2960, 33872, 411776, 5221568, 68299520, 914858240, 12486496256, 173031701504, 2428066058240, 34432752275456, 492697174507520, 7104716644990976, 103142445617709056, 1506248913346691072
Offset: 0

Views

Author

Wolfdieter Lang, Feb 05 2002

Keywords

Crossrefs

Cf. A064340 (first column), A067300 (third column).

Formula

a(n)=A067298(n+1, 1).
G.f.: ((1+x)*c(2, 2; x)-1)/x, with c(2, 2; x) := (1-3*x*c(4*x))/(1-2*x*c(4*x))^2 g.f. for A064340 and c(x) is g.f. for A000108 (Catalan).
G.f.: (2+x + 12*x*(1+x)*c(4*x))/(1+2*x)^2, where c(x) is g.f. for A000108 (Catalan). - Wolfdieter Lang, May 05 2006.
Conjecture: n*(17*n-7)*a(n) +2*(-119*n^2+270*n-96)*a(n-1) -16*(17*n+10)*(2*n-3)*a(n-2)=0. - R. J. Mathar, Jul 21 2016

A067301 One eighth of fourth column of triangle A067298.

Original entry on oeis.org

8, 41, 398, 4460, 53720, 677744, 8836832, 118109888, 1609484672, 22276767488, 312305704448, 4425515174912, 63285369657344, 912105965121536, 13235652537933824, 193215065765888000, 2835518953336438784
Offset: 0

Views

Author

Wolfdieter Lang, Feb 05 2002

Keywords

Crossrefs

Cf. 3*A067300 (third column).

Formula

a(n) = A067298(n+3, 3)/8.
G.f.: ((-3+37*x)+(3+15*x-84*x^2)*c(4*x))/(8*x*(1-2*x*c(4*x))^2), with c(x) is g.f. for A000108 (Catalan).
Showing 1-3 of 3 results.