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%I #25 Jan 14 2021 21:14:40
%S 0,1,2,3,4,5,6,7,8,9,19,18,17,16,15,14,13,12,11,10,29,28,27,26,25,24,
%T 23,22,21,20,39,38,37,36,35,34,33,32,31,30,49,48,47,46,45,44,43,42,41,
%U 40,59,58,57,56,55,54,53,52,51,50,69,68,67,66,65,64,63,62,61,60,79,78,77
%N Replace each digit d (except the leading one) of n with 9-d.
%C By definition, one-digit numbers do not change.
%C Differs from A003100 starting with a(21)=29: A003100(21)=20. A003100={0,1,2,3,4,5,6,7,8,9,19,18,17,16,15,14,13,12,11,10, 20,21,22,23,24,25,26,27,28,29,39,38,37,36,35,34,33, 32,31,30,40,41,42,43,44,45,46,47,48,49}: Decimal Gray code for n.
%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%F a(n) = n if n < 10, otherwise 2*a(floor(n/2)) + 9 - n mod 10; a self-inverse permutation of the natural numbers, A115310(n+8, 9) = a(n) for n > 0. - _Reinhard Zumkeller_, Jan 20 2006
%F a(n) = A305238(n-9) for 10 <= n <= 99. - _M. F. Hasler_, Oct 16 2018
%t a[n_]:=FromDigits[Flatten[{IntegerDigits[n][[1]], Map[9-#&, Drop[IntegerDigits[n], 1]]}]];Table[a[n], {n, 0, 100}]
%Y Cf. A003100.
%Y Cf. A054429, A115303, A115304, A115305, A115306, A115307, A115308, A115309.
%K nonn,base
%O 0,3
%A _Zak Seidov_, May 12 2005
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