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A222820 a(n) is the number of reverse multipliers for base n. 5
1, 2, 2, 3, 3, 3, 5, 4, 3, 6, 5, 4, 7, 7, 4, 8, 6, 8, 8, 7, 6, 11, 11, 6, 8, 9, 6, 13, 12, 10, 13, 6, 9, 14, 10, 9, 13, 17, 9, 15, 12, 13, 17, 13, 11, 20, 16, 12, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,2
COMMENTS
If there is a number m such that the reversal of m in base n is c times m, then c is called a reverse multiplier for n. For example, 2 is a reverse multiplier for base n=5, since 8 (base 10) = 13 (base 5), and 2*8 = 16 (base 10) = 31 (base 5).
The trivial reverse multiplier 1 is included.
a(n)-1 is the length of row n of A222817. - Michel Marcus, Apr 12 2020
REFERENCES
For a complete list of references and links related to this problem see A214927.
LINKS
N. J. A. Sloane, 2178 And All That, arXiv:1307.0453 [math.NT], 2013; see also, Fib. Quart., 52 (2014), 99-120.
Anne Ludington Young, k-Reverse multiples, Fib. Q., 30 (1992), 126-132.
CROSSREFS
See A214927 for other cross-references.
Sequence in context: A210957 A306246 A147665 * A301662 A317773 A318082
KEYWORD
nonn,more,base
AUTHOR
N. J. A. Sloane, Mar 13 2013
STATUS
approved

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Last modified March 29 03:51 EDT 2024. Contains 371264 sequences. (Running on oeis4.)