OFFSET
1,1
COMMENTS
222 is the least number k for which the repeated iterations of the mapping k -> A371418(k) seem to generate an unbounded sequence.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..1389
Robert D. Carmichael, Empirical Results in the Theory of Numbers, The Mathematics Teacher, Vol. 14, No. 6 (1921), pp. 305-310; alternative link. See p. 309.
EXAMPLE
MATHEMATICA
r[n_] := n/FactorInteger[n][[1, 1]]; f[n_] := r[DivisorSigma[1, n]]; NestList[f, 222, 60]
PROG
(PARI) f(n) = {my(s = sigma(n)); if(s == 1, 1, s/factor(s)[1, 1]); }
lista(nmax) = {my(m = 222); for(n = 1, nmax, print1(m, ", "); m = f(m)); }
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Mar 23 2024
STATUS
approved