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A091042 Triangle of even numbered entries of odd numbered rows of Pascal's triangle A007318. 24
1, 1, 3, 1, 10, 5, 1, 21, 35, 7, 1, 36, 126, 84, 9, 1, 55, 330, 462, 165, 11, 1, 78, 715, 1716, 1287, 286, 13, 1, 105, 1365, 5005, 6435, 3003, 455, 15, 1, 136, 2380, 12376, 24310, 19448, 6188, 680, 17, 1, 171, 3876, 27132, 75582, 92378, 50388, 11628, 969, 19, 1, 210, 5985, 54264, 203490, 352716, 293930, 116280, 20349, 1330, 21 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

The row polynomials Pe(n, x) := Sum_{m=0..n}(a(n, m)*x^m appear as numerators of the generating functions for the even numbered column sequences of array A034870.

Elements have the same parity as those of Pascal's triangle.

All zeros of polynomial Pe(n, x) are negative. They are -tan^2(pi/2*n+1), -tan^2(2*pi/2*n+1), ..., -tan^2(n*pi/2*n+1). Moreover, for m>=1, Pe(m, -x^2) is the characteristic polynomial of the linear difference equation with constant coefficients for differences between multiples of 2*m+1 with even and odd digit sum in base 2*m in interval [0,(2*m)^n). - Vladimir Shevelev and Peter J. C. Moses, May 22 2012

Row reverse of A103327. - Peter Bala, Jul 29 2013

The row polynomial Pe(d, x), multiplied by (2*d)!/d! = A001813(d), gives the numerator polynomial of the o.g.f. of the sequence of the diagonal d, for d >= 0, of the Sheffer triangle Lah[4,1] given in A048854. - Wolfdieter Lang, Oct 12 2017

REFERENCES

A. M. Yaglom and I. M. Yaglom, An elementary proof of the Wallis, Leibniz and Euler formulas for pi. Uspekhi Matem. Nauk, VIII (1953), 181-187(in Russian).

LINKS

Indranil Ghosh, Rows 0..120 of triangle, flattened

W. Lang, First 9 rows.

V. Shevelev, On monotonic strengthening of Newman-like phenomenon on (2m+1)-multiples in base 2m

V. Shevelev and P. Moses, Tangent power sums and their applications

FORMULA

a(n, m) = binomial(2*n+1, 2*m)=A007318(2*n+1, 2*m), n>=m>=0, else 0.

From Peter Bala, Jul 29 2013: (Start)

E.g.f.: sinh(t)*cosh(sqrt(x)*t) = t + (1 + 3*x)*t^3/3! + (1 + 10*x + 5*x^2)*t^5/5! + (1 + 21*x + 35*x^2 + 7*x^3)*t^7/7! + ....

O.g.f.: A(x,t) = (1 + (x - 1)*t)/( (1 + (x - 1)*t)^2 - 4*t*x ) = 1 + (1 + 3*x)*t + (1 + 10*x + 5*x^2)*t^2 + ...

The function A( x/(x + 4), t*(x + 4)/4 ) = 1 + (1 + x)*t + (1 + 3*x + x^2)*t^2 + ... is the o.g.f. for A085478.

O.g.f. for n-th diagonal: ( sum {k = 0..n} binomial(2*n,2*k)*x^k )/(1 - x)^(2*n).

n-th row polynomial R(n,x) = 1/2*( (1 + sqrt(x))^(2*n+1) - (sqrt(x) - 1)^(2*n+1) ).

Row sums A000302. (End)

T(n, k)=2*T(n-1,k)+2*T(n-1,k-1)+2*T(n-2,k-1)-T(n-2,k)-T(n-2,k-2) with T(0,0)=T(1,0)=1, T(1,1)=3, T(n,k)=0 if k<0 or if k>n. - Philippe Deléham, Nov 26 2013

EXAMPLE

Triangle a(n, m) begins:

n\m  0   1    2     3      4      5      6      7     8    9  10 ...

0:   1

1:   1   3

2:   1  10    5

3:   1  21   35     7

4:   1  36  126    84      9

5:   1  55  330   462    165     11

6:   1  78  715  1716   1287    286     13

7:   1 105 1365  5005   6435   3003    455     15

8:   1 136 2380 12376  24310  19448   6188    680    17

9:   1 171 3876 27132  75582  92378  50388  11628   969   19

10:  1 210 5985 54264 203490 352716 293930 116280 20349 1330  21

... reformatted and extended. - Wolfdieter Lang, Oct 12 2017

MAPLE

f := (x, t) -> cosh(sqrt(x)*t)*sinh(t); seq(seq(coeff(((2*n+1)!*coeff(series(f(x, t), t, 2*n+2), t, 2*n+1)), x, k), k=0..n), n=0..9); # Peter Luschny, Jul 29 2013

MATHEMATICA

T[n_, k_] /; 0 <= k <= n := T[n, k] = 2T[n-1, k] + 2T[n-1, k-1] + 2T[n-2, k-1] - T[n-2, k] - T[n-2, k-2]; T[0, 0] = T[1, 0] = 1; T[1, 1] = 3; T[_, _] = 0;

Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Jul 29 2018, after Philippe Deléham *)

CROSSREFS

Cf. A212500, A038754. A000302 (row sums), A085478, A103327 (row reverse), A048854.

Sequence in context: A107870 A078817 A316193 * A111418 A113187 A057967

Adjacent sequences:  A091039 A091040 A091041 * A091043 A091044 A091045

KEYWORD

nonn,easy,tabl

AUTHOR

Wolfdieter Lang, Jan 23 2004

STATUS

approved

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Last modified January 23 03:08 EST 2019. Contains 319370 sequences. (Running on oeis4.)