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 A003262 Let y=f(x) satisfy F(x,y)=0. The sequence a(n) is the number of terms in the expansion of (d^n/dx^n) y in terms of the partial derivatives of F. (Formerly M2791) 4
 1, 3, 9, 24, 61, 145, 333, 732, 1565, 3247, 6583, 13047, 25379, 48477, 91159, 168883, 308736, 557335, 994638, 1755909, 3068960, 5313318, 9118049, 15516710, 26198568, 43904123, 73056724, 120750102, 198304922, 323685343 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 175. L. Comtet and M. Fiolet, Sur les dérivées successives d'une fonction implicite. C. R. Acad. Sci. Paris Ser. A 278 (1974), 249-251. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Robert G. Wilson v, Table of n, a(n) for n = 1..500 L. Comtet, Letter to N. J. A. Sloane, Mar 1974 L. Comtet & M. Fiolet, Number of terms in an nth derivative, C. R. Acad. Sc. Paris, t. 278 (21 janvier 1974), Serie A- 249-251. (Annotated scanned copy) T. Wilde, Implicit higher derivatives and a formula of Comtet and Fiolet, arXiv:0805.2674 [math.CO], 2008. FORMULA The generating function given by Comtet and Fiolet is incorrect. a(n) = coefficient of t^n*u^(n-1) in Product_{i,j>=0,(i,j)<>(0,1)} (1 - t^i*u^(i+j-1))^(-1). - Tom Wilde (tom(AT)beech84.fsnet.co.uk), Jan 19 2008 EXAMPLE d^2y/dx^2 = -F_xx/F_y + 2*F_xF_xy/F_y^2 - F_x^2F_yy/F_y^3, where F_x denotes partial derivative with respect to x, etc. This has three terms, thus a(n)=3. MATHEMATICA ClearAll[p, q]; p[_, _] = 0; q[_, _] = 0; e = 30; For[m = 1, m <= e - 1, m++, For[d = 1, d <= m, d++, If[m == d*Floor[m/d], For[i = 0, i <= m/d + 1, i++, If[d*i <= e, q[m, i*d] = q[m, i*d] + 1/d]]]]]; For[j = 0, j <= e, j++, p[0, j] = 1]; For[n = 1, n <= e - 1, n++, For[s = 0, s <= n, s++, For[j = 0, j <= e, j++, For[i = 0, i <= j, i++, p[n, j] = p[n, j] + (1/n)*s*q[s, j - i]*p[n - s, i]]]]]; A003262 = Table[p[n - 1, n], {n, 1, e}](* Jean-François Alcover, after Tom Wilde *) PROG (VBA) ' Tom Wilde, Jan 19 2008 Sub Calc_AofN_upto_E() E = 30 ReDim p(0 To E - 1, 0 To E) ReDim q(0 To E - 1, 0 To E) For m = 1 To E - 1   For d = 1 To m     If m = d * Int(m / d) Then       For i = 0 To m / d + 1         If d * i <= E Then q(m, i * d) = q(m, i * d) + 1 / d       Next     End If   Next Next For j = 0 To E   p(0, j) = 1 Next For n = 1 To E - 1   For s = 0 To n     For j = 0 To E       For i = 0 To j         p(n, j) = p(n, j) + 1 / n * s * q(s, j - i) * p(n - s, i)       Next     Next   Next Next For n = 1 To E    Debug.Print p(n - 1, n) Next End Sub CROSSREFS Cf. A098504. Cf. A172004 (generalization to bivariate implicit functions). Cf. A162326 (analogous sequence for implicit divided differences). Cf. A172003 (bivariate variant). Sequence in context: A320731 A084858 A228820 * A189162 A079282 A117585 Adjacent sequences:  A003259 A003260 A003261 * A003263 A003264 A003265 KEYWORD nonn,nice,easy AUTHOR EXTENSIONS More terms from Tom Wilde (tom(AT)beech84.fsnet.co.uk), Jan 19 2008 STATUS approved

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Last modified November 21 11:01 EST 2018. Contains 317447 sequences. (Running on oeis4.)