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A119467
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A masked Pascal triangle.
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10
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1, 0, 1, 1, 0, 1, 0, 3, 0, 1, 1, 0, 6, 0, 1, 0, 5, 0, 10, 0, 1, 1, 0, 15, 0, 15, 0, 1, 0, 7, 0, 35, 0, 21, 0, 1, 1, 0, 28, 0, 70, 0, 28, 0, 1, 0, 9, 0, 84, 0, 126, 0, 36, 0, 1, 1, 0, 45, 0, 210, 0, 210, 0, 45, 0, 1, 0, 11, 0, 165, 0, 462, 0, 330, 0, 55, 0, 1, 1, 0, 66, 0, 495, 0, 924
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OFFSET
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0,8
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COMMENTS
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Row sums are A011782. Diagonal sums are F(n+1)*(1+(-1)^n)/2 (aerated version of A001519). Product by Pascal's triangle A007318 is A119468. Schur product of (1/(1-x),x/(1-x)) and (1/(1-x^2),x).
Exponential Riordan array (cosh(x),x). Inverse is (sech(x),x) or A119879. - Paul Barry, May 26 2006
Rows give coefficients of polynomials p_n(x) = Sum_{k=0..n} (k+1 mod 2)*binomial(n,k)*x^(n-k) having e.g.f. exp(x*t)*cosh(t)= 1*(t^0/0!) + x*(t^1/1!) + (1+x^2)*(t^2/2!) + ... - Peter Luschny, Jul 14 2009
Inverse of the coefficient matrix of the Swiss-Knife polynomials in ascending order of x^i (reversed and aerated rows of A153641). - Peter Luschny, Jul 16 2012
Call this array M and for k = 0,1,2,... define M(k) to be the lower unit triangular block array
/I_k 0\
\ 0 M/ having the k x k identity matrix I_k as the upper left block; in particular, M(0) = M. The infinite matrix product M(0)*M(1)*M(2)*... is equal to A136630 but with the first row and column omitted. - Peter Bala, Jul 28 2014
The row polynomials SKv(n,x) = [(x+1)^n + (x-1)^n]/2 , with e.g.f. cosh(t)*exp(xt), are the umbral compositional inverses of the row polynomials of A119879 (basically the Swiss Knife polynomials SK(n,x) of A153641); i.e., umbrally SKv(n,SK(.,x)) = x^n = SK(n,SKv(.,x)). Therefore, this entry's matrix and A119879 are an inverse pair. Both sequences of polynomials are Appell sequences, i.e., d/dx P(n,x) = n * P(n-1,x) and (P(.,x)+y)^n = P(n,x+y). In particular, (SKv(.,0)+x)^n = SKv(n,x), reflecting that the first column has the e.g.f. cosh(t). The raising operator is R = x + tanh(d/dx); i.e., R SKv(n,x) = SKv(n+1,x). The coefficients of this operator are basically the signed and aerated zag numbers A000182, which can be expressed as normalized Bernoulli numbers. The triangle is formed by multiplying the n-th diagonal of the lower triangular Pascal matrix by the Taylor series coefficient a(n) of cosh(x). More relations for this type of triangle and its inverse are given by the formalism of A133314. - Tom Copeland, Sep 05 2015
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LINKS
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Reinhard Zumkeller, Rows n = 0..125 of table, flattened
P. Barry, Riordan Arrays, Orthogonal Polynomials as Moments, and Hankel Transforms, J. Int. Seq. 14 (2011) # 11.2.2, example 28.
Miguel Méndez, Rafael Sánchez, On the combinatorics of Riordan arrays and Sheffer polynomials: monoids, operads and monops, arXiv:1707.00336 [math.CO}, 2017, Section 4.3, Example 4.
Miguel A. Méndez, Rafael Sánchez Lamoneda, Monops, Monoids and Operads: The Combinatorics of Sheffer Polynomials, The Electronic Journal of Combinatorics 25(3) (2018), #P3.25.
Index entries for triangles and arrays related to Pascal's triangle
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FORMULA
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G.f.: (1-xy)/(1-2xy-x^2+x^2*y^2);
T(n,k) = C(n,k)*(1+(-1)^(n-k))/2;
Column k has g.f. (1/(1-x^2)(x/(1-x^2))^k*Sum_{j=0..k+1, binomial(k+1,j)*sin((j+1)*Pi/ 2)^2*x^j}.
Column k has e.g.f. cosh(x)*x^k/k! - Paul Barry, May 26 2006
Let Pascal's triangle, A007318 = P; then this triangle = (1/2) * (P + 1/P). Also A131047 = (1/2) * (P - 1/P). - Gary W. Adamson, Jun 12 2007
Equals A007318 - A131047 since the zeros of the triangle are masks for the terms of A131047. Thus A119467 + A131047 = Pascal's triangle. - Gary W. Adamson, Jun 12 2007
T(n,k) = (A007318(n,k) + A130595(n,k))/2, 0<=k<=n. - Reinhard Zumkeller, Mar 23 2014
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EXAMPLE
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Triangle begins
1,
0, 1,
1, 0, 1,
0, 3, 0, 1,
1, 0, 6, 0, 1,
0, 5, 0, 10, 0, 1,
1, 0, 15, 0, 15, 0, 1,
0, 7, 0, 35, 0, 21, 0, 1,
1, 0, 28, 0, 70, 0, 28, 0, 1,
0, 9, 0, 84, 0, 126, 0, 36, 0, 1,
1, 0, 45, 0, 210, 0, 210, 0, 45, 0, 1
p[0](x) = 1
p[1](x) = x
p[2](x) = 1 + x^2
p[3](x) = 3*x + x^3
p[4](x) = 1 + 6*x^2 + x^4
p[5](x) = 5*x + 10*x^3 + x^5
Connection with A136630: With the arrays M(k) as defined in the Comments section, the infinite product M(0)*M(1)*M(2)*... begins
/1 \/1 \/1 \ /1 \
|0 1 ||0 1 ||0 1 | |0 1 |
|1 0 1 ||0 0 1 ||0 0 1 |... = |1 0 1 |
|0 3 0 1 ||0 1 0 1 ||0 0 0 1 | |0 4 0 1 |
|1 0 6 0 1||0 0 3 0 1||0 0 1 0 1| |1 0 10 0 1|
|... ||... ||... | |... |
- Peter Bala, Jul 28 2014
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MAPLE
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# Polynomials: p_n(x)
p := proc(n, x) local k, pow; pow := (n, k) -> `if`(n=0 and k=0, 1, n^k);
add((k+1 mod 2)*binomial(n, k)*pow(x, n-k), k=0..n) end;
# Coefficients: a(n)
seq(print(seq(coeff(i!*coeff(series(exp(x*t)*cosh(t), t, 16), t, i), x, n), n=0..i)), i=0..8); # Peter Luschny, Jul 14 2009
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MATHEMATICA
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Table[Binomial[n, k] (1 + (-1)^(n - k))/2, {n, 0, 12}, {k, 0, n}] // Flatten (* Michael De Vlieger, Sep 06 2015 *)
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PROG
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(Sage)
@CachedFunction
def A119467_poly(n, x) :
return 1 if n==0 else add(binomial(n, k)*(x^(n-k)) for k in range(n+1)[::2])
def A119467_row(n) :
R = PolynomialRing(ZZ, 'x')
return R(A119467_poly(n, x)).coeffs()
for n in (0..10) : print A119467_row(n) # Peter Luschny, Jul 16 2012
(Haskell)
a119467 n k = a119467_tabl !! n !! k
a119467_row n = a119467_tabl !! n
a119467_tabl = map (map (flip div 2)) $
zipWith (zipWith (+)) a007318_tabl a130595_tabl
-- Reinhard Zumkeller, Mar 23 2014
(MAGMA) /* As triangle */ [[Binomial(n, k)*(1 + (-1)^(n - k))/2: k in [0..n]]: n in [0.. 15]]; // Vincenzo Librandi, Sep 26 2015
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CROSSREFS
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Cf. A131047, A153641.
From Peter Luschny, Jul 14 2009: (Start)
Cf. A034839, A162590.
p[n](k), n=0,1,...
k= 0: 1, 0, 1, 0, 1, 0, ... A128174
k= 1: 1, 1, 2, 4, 8, 16, ... A011782
k= 2: 1, 2, 5, 14, 41, 122, ... A007051
k= 3: 1, 3, 10, 36, 136, ... A007582
k= 4: 1, 4, 17, 76, 353, ... A081186
k= 5: 1, 5, 26, 140, 776, ... A081187
k= 6: 1, 6, 37, 234, 1513, ... A081188
k= 7: 1, 7, 50, 364, 2696, ... A081189
k= 8: 1, 8, 65, 536, 4481, ... A081190
k= 9: 1, 9, 82, 756, 7048, ... A060531
k=10: 1, 10, 101, 1030, ... A081192
p[n](k), k=0,1,...
p[0]: 1,1,1,1,1,1, ....... A000012
p[1]: 0,1,2,3,4,5, ....... A001477
p[2]: 1,2,5,10,17,26, .... A002522
p[3]: 0,4,14,36,76,140, .. A079908 (End)
Cf. A000182, A133314, A153641.
Sequence in context: A112743 A230427 A229995 * A166353 A110235 A036856
Adjacent sequences: A119464 A119465 A119466 * A119468 A119469 A119470
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KEYWORD
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easy,nonn,tabl,look
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AUTHOR
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Paul Barry, May 21 2006
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EXTENSIONS
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Edited by N. J. A. Sloane, Jul 14 2009
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STATUS
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approved
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