This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A222819 #32 Jan 09 2025 10:16:56 %S A222819 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, %T A222819 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, %U A222819 23,14,15,21,19,14,19,12,18,16,19,17,26,17,11,20,16,15,21,13,26,24,13 %N A222819 a(n) = number of nontrivial reverse multipliers for base n. %C A222819 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 A222819 The trivial reverse multiplier 1 is excluded. %H A222819 N. J. A. Sloane, <a href="/A222819/b222819.txt">Table of n, a(n) for n = 2..100</a> %H A222819 N. J. A. Sloane, <a href="http://arxiv.org/abs/1307.0453">2178 And All That</a>, Fib. Quart., 52 (2014), 99-120. %H A222819 N. J. A. Sloane, <a href="/A001232/a001232.pdf">2178 And All That</a> [Local copy] %H A222819 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. %Y A222819 Cf. A214927, A222817, A222818, A222820. %Y A222819 See A214927 for other cross-references. %K A222819 nonn,base %O A222819 2,4 %A A222819 _N. J. A. Sloane_, Mar 13 2013