

A097024


Numbers in the 5cycleattractor if the function f(x)=A063919(x) is iterated; f(x) is the sum of unitary proper divisors.


23




OFFSET

1,1


COMMENTS

A002827 provides 1cycle terms = unitary perfect numbers.
A063991 gives 2cycle elements = unitary amicable numbers.
A097030 collects true 14cycle elements, i.e., terms in endcycle of length 14 when A063919(x) function is iterated.
Concerning 3cycle elements, only {30,42,54} were encountered.


LINKS

Table of n, a(n) for n=1..5.
J. O. M. Pedersen, Order 5 cycles, 2007.


PROG

(PARI) f(n) = sumdiv(n, d, if(gcd(d, n/d)==1, d))  n;
isok5(n) = iferr(f(f(f(f(f(n))))) == n, E, 0);
isok1(n) = iferr(f(n) == n, E, 0);
isok(n) = !isok1(n) && isok5(n); \\ Michel Marcus, Sep 28 2018


CROSSREFS

Cf. A063919, A002827, A063991, A097030.
Sequence in context: A255789 A159719 A052167 * A253331 A158770 A252366
Adjacent sequences: A097021 A097022 A097023 * A097025 A097026 A097027


KEYWORD

nonn,more


AUTHOR

Labos Elemer, Aug 30 2004


STATUS

approved



