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Numbers m such that m, m+1 and 2*m have the same number of distinct digits in decimal representation.
4

%I #13 Sep 19 2024 18:49:02

%S 0,1,2,3,4,12,13,14,15,16,17,18,19,20,23,24,25,26,27,28,29,30,31,34,

%T 35,36,37,38,39,40,41,42,45,46,47,48,49,50,56,57,58,59,61,72,83,94,

%U 100,102,103,104,105,107,108,112,113,114,116,121,123,124,125,127,128,129,134

%N Numbers m such that m, m+1 and 2*m have the same number of distinct digits in decimal representation.

%C A043537(a(n)) = A043537(a(n)+1) = A043537(2*a(n));

%C intersection of A119797 and A119798.

%H Reinhard Zumkeller, <a href="/A119799/b119799.txt">Table of n, a(n) for n = 1..10000</a>

%e m=59: m, m+1 and 2*m are composed of two distinct digits:

%e 59, 59+1=60 and 2*59=118: therefore 59 is a term.

%t Select[Range[0,134],CountDistinct[IntegerDigits[#]]==CountDistinct[IntegerDigits[2#]]==CountDistinct[IntegerDigits[#+1]]&] (* _James C. McMahon_, Sep 19 2024 *)

%o (Haskell)

%o a119799 n = a119799_list !! (n-1)

%o a119799_list = i a119797_list a119798_list where

%o i xs'@(x:xs) ys'@(y:ys) | x < y = i xs ys'

%o | x > y = i xs' ys

%o | otherwise = x : i xs ys

%o -- _Reinhard Zumkeller_, Jan 04 2012

%K nonn,base

%O 1,3

%A _Reinhard Zumkeller_, May 25 2006

%E Offset fixed by _Reinhard Zumkeller_, Jan 04 2012