login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Table of n, a(n) for n=0..23.

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

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