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A243843 a(n) is the smallest semiprime that belongs to a cycle of length n under repeated iteration of the map (k -> concatenation of prime divisors of k) until a non-semiprime is reached. 0
6, 38, 34, 15, 265, 161, 1126, 4891, 1253, 250231, 100462, 49869178, 234139657, 68279314 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..14.

Carlos Rivera, Puzzle 640

CROSSREFS

Sequence in context: A083373 A320988 A015492 * A039293 A055713 A216384

Adjacent sequences:  A243840 A243841 A243842 * A243844 A243845 A243846

KEYWORD

nonn,base,hard,more

AUTHOR

Arkadiusz Wesolowski, Jun 13 2014

STATUS

approved

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Last modified May 25 22:51 EDT 2022. Contains 354073 sequences. (Running on oeis4.)