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 A076256 Coefficients of the polynomials in the numerator of 1/(1+x^2) and its successive derivatives, starting with the constant term. 3
 1, 0, -2, -2, 0, 6, 0, 24, 0, -24, 24, 0, -240, 0, 120, 0, -720, 0, 2400, 0, -720, -720, 0, 15120, 0, -25200, 0, 5040, 0, 40320, 0, -282240, 0, 282240, 0, -40320, 40320, 0, -1451520, 0, 5080320, 0, -3386880, 0, 362880, 0, -3628800, 0, 43545600, 0, -91445760, 0, 43545600 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Denominator of n-th derivative is (1+x^2)^(n+1), whose coefficients are the binomial coefficients, A007318. LINKS FORMULA For 0<=k<=n, let a(n, k) be the coefficient of x^k in the numerator of the n-th derivative of 1/(1+x^2). If n+k is even, a(n, k) = (-1)^((n+k)/2)*n!*binomial(n+1, k); if n+k is odd, a(n, k)=0. EXAMPLE The coefficients of the numerators starting with the constant term are 1; 0,-2; -2,0,6; 0,24,0,-24; ... MATHEMATICA a[n_, k_] := Coefficient[Expand[Together[(1+x^2)^(n+1)*D[1/(1+x^2), {x, n}]]], x, k]; Flatten[Table[a[n, k], {n, 0, 10}, {k, 0, n}]] CROSSREFS Cf. A076257, A076741, A076743. Sequence in context: A221337 A157077 A185896 * A127467 A338001 A271708 Adjacent sequences:  A076253 A076254 A076255 * A076257 A076258 A076259 KEYWORD sign,tabl,easy AUTHOR Mohammad K. Azarian, Nov 05 2002 EXTENSIONS Edited by Dean Hickerson, Nov 28 2002 STATUS approved

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Last modified April 17 04:36 EDT 2021. Contains 343059 sequences. (Running on oeis4.)