cp's OEIS Frontend

A222817 Irregular triangle read by rows: row n gives list of nontrivial reverse multipliers for base n.

%I A222817 #32 Jan 09 2025 10:15:33
%S A222817 2,3,2,4,2,5,3,6,2,3,5,7,2,4,8,4,9,2,3,5,7,10,2,3,5,11,5,6,12,2,3,4,6,
%T A222817 9,13,2,3,4,7,11,14,3,7,15,2,4,5,8,10,11,16,2,5,7,8,17,3,4,6,7,9,14,
%U A222817 18,2,3,4,6,9,13,19
%N A222817 Irregular triangle read by rows: row n gives list of nontrivial reverse multipliers for base n.
%C A222817 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).
%C A222817 The trivial reverse multiplier 1 is excluded.
%C A222817 The last entry in each row is n-1; the number of terms in row n is A222819(n).
%H A222817 N. J. A. Sloane, <a href="/A222817/a222817.txt">Table giving n,  list of nontrivial reverse multipliers, for n = 3..100</a>
%H A222817 N. J. A. Sloane, <a href="http://arxiv.org/abs/1307.0453">2178 And All That</a>, arXiv:1307.0453 [math.NT], 2013; Fib. Quart., 52 (2014), 99-120.
%H A222817 N. J. A. Sloane, <a href="/A001232/a001232.pdf">2178 And All That</a> [Local copy]
%H A222817 Anne Ludington Young, <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Scanned/30-2/ludington1.pdf">k-Reverse multiples</a>, Fib. Q., 30 (1992), 126-132.
%e A222817 Triangle begins:
%e A222817   2,
%e A222817   3,
%e A222817   2,4,
%e A222817   2,5,
%e A222817   3,6,
%e A222817   2,3,5,7,
%e A222817   2,4,8,
%e A222817   4,9,
%e A222817   2,3,5,7,10,
%e A222817   2,3,5,11,
%e A222817   5,6,12,
%e A222817   2,3,4,6,9,13,
%e A222817   2,3,4,7,11,14,
%e A222817   3,7,15,
%e A222817   ...
%Y A222817 Cf. A214927, A222818, A222819, A222820.
%Y A222817 See A214927 for other cross-references.
%K A222817 nonn,tabf
%O A222817 3,1
%A A222817 _N. J. A. Sloane_, Mar 13 2013