A051159 Triangle read by rows: T(n, k) = binomial(n mod 2, k mod 2) * binomial(n div 2, k div 2), where 'div' denotes integer division.
1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 2, 0, 1, 1, 1, 2, 2, 1, 1, 1, 0, 3, 0, 3, 0, 1, 1, 1, 3, 3, 3, 3, 1, 1, 1, 0, 4, 0, 6, 0, 4, 0, 1, 1, 1, 4, 4, 6, 6, 4, 4, 1, 1, 1, 0, 5, 0, 10, 0, 10, 0, 5, 0, 1, 1, 1, 5, 5, 10, 10, 10, 10, 5, 5, 1, 1, 1, 0, 6, 0, 15, 0, 20, 0, 15, 0, 6, 0, 1, 1, 1, 6, 6, 15, 15, 20, 20, 15, 15, 6, 6, 1, 1
Offset: 0
Examples
Triangle starts: {1}, {1, 1}, {1, 0, 1}, {1, 1, 1, 1}, {1, 0, 2, 0, 1}, {1, 1, 2, 2, 1, 1}, {1, 0, 3, 0, 3, 0, 1}, {1, 1, 3, 3, 3, 3, 1, 1}, {1, 0, 4, 0, 6, 0, 4, 0, 1}, {1, 1, 4, 4, 6, 6, 4, 4, 1, 1}, {1, 0, 5, 0, 10, 0, 10, 0, 5, 0, 1}, {1, 1, 5, 5, 10, 10, 10, 10, 5, 5, 1, 1} ... - _Roger L. Bagula_ and _Gary W. Adamson_, Dec 04 2009
Links
- Reinhard Zumkeller, Rows n = 0..120 of triangle, flattened
- Paul Barry, Jacobsthal Decompositions of Pascal's Triangle, Ternary Trees, and Alternating Sign Matrices, Journal of Integer Sequences, 19, 2016, #16.3.5.
- Nantel Bergeron, Kelvin Chan, Yohana Solomon, Farhad Soltani, and Mike Zabrocki, Quasisymmetric harmonics of the exterior algebra, arXiv:2206.02065 [math.CO], 2022.
- E. Burlachenko, Fractal generalized Pascal matrices, arXiv:1612.00970 [math.NT], 2016. See p. 3.
- S. J. Cyvin, B. N. Cyvin, and J. Brunvoll, Unbranched catacondensed polygonal systems containing hexagons and tetragons, Croatica Chem. Acta, 69 (1996), 757-774. See Table 1 on p. 763.
- D. E. Davenport, L. W. Shapiro and L. C. Woodson, The Double Riordan Group, The Electronic Journal of Combinatorics, 18(2) (2012).
- M. E. Horn, The Didactical Relevance of the Pauli Pascal Triangle, arXiv:physics/0611277 [physics.ed-ph], 2006. [_Michael Somos_]
- F. Al-Kharousi, R. Kehinde, and A. Umar, Combinatorial results for certain semigroups of partial isometries of a finite chain, The Australasian Journal of Combinatorics, Volume 58 (3) (2014), 363-375.
- P. A. MacMahon, Memoir on the Theory of the Compositions of Numbers, Phil. Trans. Royal Soc. London A, 184 (1893), 835-901.
- Index entries for triangles and arrays related to Pascal's triangle
Programs
-
Haskell
a051159 n k = a051159_tabl !! n !! k a051159_row n = a051159_tabl !! n a051159_tabl = [1] : f [1] [1,1] where f us vs = vs : f vs (zipWith (+) ([0,0] ++ us) (us ++ [0,0])) -- Reinhard Zumkeller, Apr 25 2013
-
Maple
T:= proc(n, k) option remember; `if`(n=0 and k=0, 1, `if`(n<0 or k<0, 0, `if`(irem(n, 2)=1 or irem(k, 2)=0, T(n-1, k-1) + T(n-1, k), 0))) end: seq(seq(T(n, k), k=0..n), n=0..14); # Alois P. Heinz, Jul 12 2014
-
Mathematica
T[ n_, k_] := QBinomial[n, k, -1]; (* Michael Somos, Jun 14 2011; since V7 *) Clear[p, n, x, a] w = 0; p[x, 1] := 1; p[x_, n_] := p[x, n] = If[Mod[n, 2] == 0, (x + 1)*p[x, n - 1], (x^2 + w*x + 1)^Floor[n/2]] a = Table[CoefficientList[p[x, n], x], {n, 1, 12}] Flatten[a] (* Roger L. Bagula and Gary W. Adamson, Dec 04 2009 *)
-
PARI
{T(n, k) = binomial(n%2, k%2) * binomial(n\2, k\2)};
-
Python
from math import comb as binomial def T(n, k): return binomial(n%2, k%2) * binomial(n//2, k//2) print([T(n, k) for n in range(14) for k in range(n+1)]) # Peter Luschny, Oct 17 2024
-
SageMath
@cached_function def T(n, k): if k == 0 or k == n: return 1 return T(n-1, k-1) + (-1)^k*T(n-1, k) for n in (0..12): print([T(n, k) for k in (0..n)]) # Peter Luschny, Jul 06 2021
Formula
T(n, k) = T(n-1, k-1) + T(n-1, k) if n odd or k even, else 0. T(0, 0) = 1.
T(n, k) = T(n-2, k-2) + T(n-2, k). T(0, 0) = T(1, 0) = T(1, 1) = 1.
Square array made by setting first row/column to 1's (A(i, 0) = A(0, j) = 1); A(1, 1) = 0; A(1, j) = A(1, j-2); A(i, 1) = A(i-2, 1); other entries A(i, j) = A(i-2, j) + A(i, j-2). - Gerald McGarvey, Aug 21 2004
Sum_{k=0..n} k * T(n,k) = A093968(n); A093968 = S-D transform of A001477. - Philippe Deléham, Aug 02 2006
Equals 2*A034851 - A007318. - Gary W. Adamson, Dec 31 2007. [Corrected by Yosu Yurramendi, Aug 07 2008]
A051160(n, k) = (-1)^floor(k/2) * T(n, k).
Sum_{k = 0..n} T(n,k)*x^k = A000012(n), A016116(n+1), A056487(n), A136859(n+2) for x = 0, 1, 2, 3 respectively. - Philippe Deléham, Mar 11 2014
G.f.: (1+x+x*y)/(1-x^2-y^2*x^2). - Philippe Deléham, Mar 11 2014
For n,k >= 1, T(n, k) = 0 when n odd and k even; otherwise, T(n, k) = binomial(floor((n-1)/2), floor((k-1)/2)). - Christian Barrientos, Mar 14 2020
From Werner Schulte, Jun 25 2021: (Start)
T(n,k) = T(n-1,k-1) + (-1)^k * T(n-1,k) for 0 < k < n with initial values T(n,0) = T(n,n) = 1 for n >= 0.
Matrix inverse is T^-1(n,k) = (-1)^((n-k)*(n+k+1)/2) * T(n,k) for 0 <= k <= n. (End)
From Peter Bala, Aug 08 2021: (Start)
Double Riordan array ( 1/(1 - x); x/(1 + x), x/(1 - x) ) in the notation of Davenport et al.
G.f. for column 2*n: (1 + x)*x^(2*n)/(1 - x^2)^(n+1); G.f. for column 2*n+1: x^(2*n+1)/(1 - x^2)^(n+1)
Row polynomials: R(2*n,x) = (1 + x^2)^n; R(2*n+1,x) = (1 + x)*(1 + x^2)^n.
The infinitesimal generator of this triangle has the sequence [1, 0, 1, 0, 1, 0, ...] on the main subdiagonal, the sequence [1, 1, 2, 2, 3, 3, 4, 4, ...] on the diagonal immediately below and zeros elsewhere.
Let T denote this lower triangular array. Then T^a, for a in C, is the double Riordan array ( (1 + a*x)/(1 - a*x^2); x/(1 + a*x), (1 + a*x)/(1 - a*x^2) ) with o.g.f. (1 + x*(a + y))/(1 - x^2*(a + y^2)) = 1 + (a + y)*x + (a + y^2)*x^2 + (a^2 + a*y + a*y^2 + y^3)*x^3 + (a^2 + 2*a*y^2 + y^4)*x^4 + ....
The (2*n)-th row polynomial of T^a is (a + y^2)^n; The (2*n+1)-th row polynomial of T^a is (a + y)*(a + y^2)^n. (End)
Extensions
New name using a formula of the author by Peter Luschny, Oct 17 2024
Comments