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A239419 Numbers that end in the trivial cycle (0) under the rule: next term = product of the last three digits of the concatenated preceding terms. 5
0, 3, 5, 7, 8, 10, 15, 16, 17, 20, 25, 30, 33, 35, 36, 40, 41, 45, 50, 51, 52, 53, 54, 55, 56, 58, 59, 60, 61, 63, 65, 67, 70, 74, 75, 76, 77, 78, 79, 80, 84, 85, 88, 89, 90, 95, 97, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 115, 116, 117, 120, 123, 125, 130, 132, 135, 136, 140, 145, 150, 151, 152, 153, 154, 155, 156, 157, 158 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Additional rule: As long as there are less than k=3 digits in the sequence, the first digit is repeated as often as necessary, e.g. 3 => 3*3*3 = 27 => 3*2*7 = 42 => 7*4*2 = 56 => 2*5*6 = 60 => 6*6*0 = 0 => 6*0*0 => 0, ...
See A238984 for more details, motivation and links.
LINKS
PROG
(PARI) is_A239419(n) = !A238984(99, n) \\ Here, the somewhat arbitrary value 99 (number of iterations before checking for 0) should be sufficiently large for small n, but might need to be increased for larger starting values n.
CROSSREFS
Sequence in context: A088759 A227130 A258025 * A195439 A338446 A190719
KEYWORD
nonn,base
AUTHOR
M. F. Hasler, Aug 01 2014
STATUS
approved

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Last modified September 16 11:35 EDT 2024. Contains 375965 sequences. (Running on oeis4.)