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 A304371 Number of function calls of the second kind required to compute ack(3,n), where ack denotes the Ackermann function. 2
 5, 47, 257, 1187, 5093, 21095, 85865, 346475, 1391981, 5580143, 22345073, 89429363, 357815669, 1431459191, 5726229881, 22905705851, 91624396157, 366500730239, 1466009212289, 5864049431939, 23456222893445, 93824941905287, 375299868284297, 1501199674463627 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS The distinction between different kinds of recursive calls is based on a naive implementation of the Ackermann function in C. int ack(int m, int n) { // Final result ....if (m==0) return n + 1; . // Recursive calls of the first kind: ....if (n==0) return ack(m - 1, 1); . // Recursive calls of the second kind: ....return ack(m - 1, ack(m, n - 1)); } LINKS Index entries for linear recurrences with constant coefficients, signature (8,-21,22,-8). FORMULA A304370(n) + a(n) + 1 = A074877(n). G.f.: (8*x^3-14*x^2+7*x+5)/((4*x-1)*(2*x-1)*(x-1)^2). - Alois P. Heinz, May 12 2018 MATHEMATICA LinearRecurrence[{8, -21, 22, -8}, {5, 47, 257, 1187}, 30] (* Harvey P. Dale, Oct 22 2019 *) CROSSREFS Cf. A036563, A074877, A304370. Sequence in context: A139889 A134327 A122501 * A049281 A219073 A327595 Adjacent sequences:  A304368 A304369 A304370 * A304372 A304373 A304374 KEYWORD nonn,easy AUTHOR Olivier Gérard, May 11 2018 STATUS approved

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Last modified March 31 03:48 EDT 2020. Contains 333136 sequences. (Running on oeis4.)