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 A222820 #26 Jan 09 2025 10:17:25 %S A222820 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, %T A222820 6,9,14,10,9,13,17,9,15,12,13,17,13,11,20,16,12,12 %N A222820 a(n) is the number of reverse multipliers for base n. %C A222820 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 A222820 The trivial reverse multiplier 1 is included. %C A222820 a(n)-1 is the length of row n of A222817. - _Michel Marcus_, Apr 12 2020 %D A222820 For a complete list of references and links related to this problem see A214927. %H A222820 N. J. A. Sloane, <a href="http://arxiv.org/abs/1307.0453">2178 And All That</a>, arXiv:1307.0453 [math.NT], 2013; see <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Papers1/52-2/Sloan10242013.pdf">also</a>, Fib. Quart., 52 (2014), 99-120. %H A222820 N. J. A. Sloane, <a href="/A001232/a001232.pdf">2178 And All That</a> [Local copy] %H A222820 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 A222820 Cf. A214927, A222817, A222818, A222819. %Y A222820 See A214927 for other cross-references. %K A222820 nonn,more,base %O A222820 2,2 %A A222820 _N. J. A. Sloane_, Mar 13 2013