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A371423
Aliquot-like sequence based on the largest aliquot divisor of the sum of divisors of n (A371418) that starts with 222.
4
222, 228, 280, 360, 585, 546, 672, 1008, 1612, 1568, 1197, 1040, 1302, 1536, 2046, 2304, 949, 518, 456, 600, 930, 1152, 1105, 756, 1120, 1512, 2400, 3906, 4992, 7140, 12096, 20320, 24192, 40800, 70308, 108416, 135660, 241920, 490560, 902208, 1235456, 1309440, 2354688
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
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
a(1) = 222 by definition.
a(2) = A371418(a(1)) = A371418(222) = 228.
a(3) = A371418(a(2)) = A371418(228) = 280.
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
Similar sequences: A008892, A323328, A361421.
Sequence in context: A078251 A092625 A043612 * A345521 A345775 A361628
KEYWORD
nonn
AUTHOR
Amiram Eldar, Mar 23 2024
STATUS
approved