A062946 Numbers that have a larger multiple which differs in just one digit from its reverse.

1, 2, 3, 4, 12, 13, 14, 16, 17, 19, 21, 23, 24, 25, 26, 28, 31, 37, 42, 47, 49, 102, 103, 109, 133, 147, 159, 166, 197, 199, 201, 204, 208, 218, 233, 247, 295, 296, 298, 301, 397, 402, 497, 499, 1002, 1003, 1009, 1019, 1029, 1038, 1039, 1049, 1059, 1069

Offset

1,2

Comments

From Robert Israel, Mar 12 2023: (Start)

The number and its multiple must have the same number of digits.

Infinite families of terms include 10^n + 2, 10^n + 3, 10^n + 9, (4*10^n - 1)/3, 1.5*10^n + 9, (5*10^n - 1)/3, 2*10^n - 3, 2*10^n - 1, 2*10^n + 1, 2*10^n + 4, 2*10^n+8, 3*10^n - 5, 3*10^n - 4, 3*10^n - 2, 3*10^n + 1, (7*10^n - 1)/3, 4*10^n - 3, 4*10^n + 2, 5*10^n - 3, 5*10^n - 1. (End)

Links

Robert Israel, Table of n, a(n) for n = 1..215

Example

1997*3=5991, which differs in just one digit from 7991, the reverse of 1997.

Maple

filter:= proc(n) local L, d, m, Lp;
 L:= ListTools:-Reverse(convert(n, base, 10));
 d:= nops(L)-1;
 for m from 2*n by n while ilog10(m) = d do
   Lp:= convert(m, base, 10);
   if nops(subs(0=NULL, L-Lp) = 1 then return true fi;
 od;
 false
end proc:
select(filter, [seq($ (10^d) .. (5*10^d-1), d=0..4)]); # Robert Israel, Mar 12 2023

Crossrefs

Sequence in context: A036779 A037339 A285618 * A210584 A060529 A048073

Adjacent sequences: A062943 A062944 A062945 * A062947 A062948 A062949

Keyword

base,nonn

Author

Erich Friedman, Jul 21 2001

Extensions

Offset changed by Robert Israel, Mar 12 2023

Status

approved