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%I #23 May 15 2021 12:35:15
%S 10,13,14,15,16,17,18,19,90,1011,100,0,0,0,0,0,0,0,0,1021,1090,103,0,
%T 0,0,0,0,0,0,1031,1080,0,104,0,0,0,0,0,0,1041,1070,0,0,105,0,0,0,0,0,
%U 1051,1060,0,0,0,106,0,0,0,0,1061,1050,0,0,0,0,107,0,0,0,1071,1040,0,0,0,0,0
%N Smallest number k such that abs(k - R(k)) = 9n, where R(k) is digit reversal of k (A004086); or 0 if no such k exists.
%C If 9n < 1000, k has at most 5 digits, and abs(k - R(k)) = 9n, then 10 must divide n. - _Sascha Kurz_, Jan 02 2003
%t a = Table[0, {50}]; Do[d = Abs[n - FromDigits[ Reverse[ IntegerDigits[n]]]] / 9; If[d < 51 && a[[d]] == 0, a[[d]] = n], {n, 1, 10^7}]; a
%o (Python)
%o def back_difference(n):
%o r = int(str(n)[::-1])
%o return abs(r-n)
%o def a070837(n):
%o i = 0
%o while True:
%o if back_difference(i)==9*n:
%o return i
%o i+=1
%o # _Christian Perfect_, Jul 23 2015
%Y Cf. A004086, A056965, A070838.
%K base,nonn
%O 1,1
%A _Amarnath Murthy_, May 12 2002
%E More terms from _Sascha Kurz_, Jan 02 2003
%E a(21) corrected by _Christian Perfect_, Jul 23 2015
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