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A222819 a(n) = number of nontrivial reverse multipliers for base n. 5
0, 1, 1, 2, 2, 2, 4, 3, 2, 5, 4, 3, 6, 6, 3, 7, 5, 7, 7, 6, 5, 10, 10, 5, 7, 8, 5, 12, 11, 9, 12, 5, 8, 13, 9, 8, 12, 16, 8, 14, 11, 12, 16, 12, 10, 19, 15, 11, 11, 9, 10, 19, 18, 17, 18, 13, 9, 23, 14, 15, 21, 19, 14, 19, 12, 18, 16, 19, 17, 26, 17, 11, 20, 16, 15, 21, 13, 26, 24, 13 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,4

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 excluded.

LINKS

N. J. A. Sloane, Table of n, a(n) for n = 2..100

N. J. A. Sloane, 2178 And All That, Fib. Quart., 52 (2014), 99-120.

Anne Ludington Young, k-Reverse multiples, Fib. Q., 30 (1992), 126-132.

CROSSREFS

Cf. A214927, A222817, A222818, A222820.

See A214927 for other cross-references.

Sequence in context: A121806 A056944 A283681 * A194319 A208609 A249030

Adjacent sequences:  A222816 A222817 A222818 * A222820 A222821 A222822

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Mar 13 2013

STATUS

approved

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Last modified May 17 21:11 EDT 2021. Contains 343990 sequences. (Running on oeis4.)