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Concatenation of largest and smallest digits of n in decimal representation.
2

%I #11 Jan 27 2014 12:30:21

%S 11,22,33,44,55,66,77,88,99,10,11,21,31,41,51,61,71,81,91,20,21,22,32,

%T 42,52,62,72,82,92,30,31,32,33,43,53,63,73,83,93,40,41,42,43,44,54,64,

%U 74,84,94,50,51,52,53,54,55,65,75,85,95,60,61,62,63,64,65,66,76,86,96

%N Concatenation of largest and smallest digits of n in decimal representation.

%C 10 <= a(n) <= 99; a(a(n))=a(n).

%H Reinhard Zumkeller, <a href="/A073730/b073730.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A054055(n)*10 + A054054(n).

%e a(12321)=31; a(3210123)=30; a(59387)=83; a(8923)=92.

%t Table[FromDigits[{Max[x = IntegerDigits[n]], Min[x]}], {n, 69}] (* _Jayanta Basu_, Jul 08 2013 *)

%o (Haskell)

%o a073730 n = 10 * a054055 n + a054054 n

%o -- _Reinhard Zumkeller_, Jul 21 2013

%Y Cf. A073729.

%K nonn,base,look

%O 1,1

%A _Reinhard Zumkeller_, Aug 05 2002