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A094796
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Triangle read by rows giving coefficients of polynomials arising in successive differences of central binomial numbers.
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3
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1, 3, 1, 9, 15, 6, 27, 108, 135, 42, 81, 594, 1539, 1530, 456, 243, 2835, 12555, 25245, 22122, 6120, 729, 12393, 83835, 281475, 482436, 383292, 101520, 2187, 51030, 489888, 2466450, 6916833, 10546200, 7786692, 1980720
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OFFSET
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0,2
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COMMENTS
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Let D_0(n)=binomial(2*n,n) and D_{k+1}(n)=D_{k}(n+1)-D_{k}(n); then D_{k}(n)*(n+1)*(n+2)*...*(n+k) = binomial(2*n,n)*P_{k}(n) where P_{k} is a polynomial with integer coefficients of degree k.
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LINKS
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FORMULA
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EXAMPLE
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The third differences of the central binomial numbers are given by D_3(n) = binomial(2*n,n)*(n+1)*(n+2)*(n+3)*(27*n^3 + 108*n^2 + 135*n + 42) and the fourth row of the triangle is 27, 108, 135, 42.
The table reads:
n | row(n)
0 | 1
1 | 3 1
2 | 9 15 6
3 | 27 108 135 42
4 | 81 594 1539 1530 456
5 | 243 2835 12555 25245 22122 6120
6 | 729 12393 83835 281475 482436 383292 101520
7 | 2187 51030 489888 2466450 6916833 10546200 7786692 1980720
8 | 6561 201204 2602530 18329976 75981969 186899076 260520300 181218384 44634240
(End)
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MAPLE
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Dnk := proc(n, k)
option remember;
if k < 0 then
0 ;
elif k = 0 then
binomial(2*n, n) ;
else
procname(n+1, k-1)-procname(n, k-1) ;
end if;
end proc:
local xyvec, i, x ;
xyvec := [] ;
for i from 0 to n do
xyvec := [op(xyvec), [i, Dnk(i, n)*mul(i+j, j=1..n)/Dnk(i, 0)]] ;
end do:
CurveFitting[PolynomialInterpolation](xyvec, x) ;
coeff(%, x, n-k) ;
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MATHEMATICA
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Dnk[n_, k_] := Dnk[n, k] = Which[k < 0, 0, k == 0, Binomial[2*n, n], True, Dnk[n + 1, k - 1] - Dnk[n, k - 1]];
T[n_, k_] := Module[{xyvec, i, x , ip}, xyvec = {}; For[i = 0, i <= n, i++, AppendTo[xyvec, {i, Dnk[i, n]*Product[i + j, {j, 1, n}]/Dnk[i, 0]}]]; ip = InterpolatingPolynomial[xyvec, x]; Coefficient[ip, x, n - k]];
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PROG
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(PARI) apply( {A094796_row(n, D(n, k)=if(k, D(n+1, k-1)-D(n, k-1), binomial(2*n, n)))=Vec(polinterpolate([0..n], vector(n+1, k, D(k--, n)*(n+k)!/k!/binomial(2*k, k))))}, [0..8]) \\ M. F. Hasler, Nov 15 2019
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CROSSREFS
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Cf. A000984 (central binomial coefficients), A163771 (square array of central binomial coefficients and higher differences), A000244 (column k=0).
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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