A097035 - OEIS

A097035

Initial values for the iteration of the function f(x) = A063919(x) such that the iteration ends in a 5-cycle, i.e., in A097024.

570, 870, 1230, 1290, 1326, 1482, 1530, 1686, 1698, 1710, 1794, 1866, 1878, 1890, 2058, 2070, 2142, 2154, 2166, 2178, 2238, 2250, 2502, 2802, 2814, 3042, 3222, 3630, 3702, 3714, 3726, 4350, 4494, 4506, 4518, 4914, 5010, 5142, 5154, 5166, 5284, 5418

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..42.

EXAMPLE

n = 570: list = {570, 870, 1290, [1878, 1890, 2142, 2178, 1482], 1878}; after 3 transients, a 5-cycle arises.

n = 1230: {1230, 1794, 2238, 2250, 1530, 1710, [1890, 2142, 2178, 1482, 1878]} ; the iteration to the 5-cycle is not necessarily monotone. - Hartmut F. W. Hoft, Jan 25 2024

MATHEMATICA

a063919[1] = 1; (* function a[] in A063919 by Jean-François Alcover *)

a063919[n_] := Total[Select[Divisors[n], GCD[#, n/#]==1&]]-n/; n>1

a097035Q[k_] := Module[{iter=NestWhileList[a063919, k, UnsameQ, All]}, Apply[Subtract, Reverse[Flatten[Position[iter, Last[iter]], 1]]]==5]

a097035[n_] := Select[Range[n], a097035Q]

a097035[5418] (* Hartmut F. W. Hoft, Jan 25 2024 *)

CROSSREFS

Cf. A002827, A063919, A063991, A097024, A097030-A097037.

Sequence in context: A252465 A252473 A252466 * A074907 A231140 A268203

Adjacent sequences: A097032 A097033 A097034 * A097036 A097037 A097038

KEYWORD

nonn

AUTHOR

Labos Elemer, Aug 30 2004

STATUS

approved