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%I #16 May 22 2020 01:12:30
%S 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,
%T 26,27,28,29,39,38,37,36,35,34,33,32,31,30,40,41,42,43,44,45,46,47,48,
%U 49,59,58,57,56,55,54,53,52,51,50,60,61,62,63,64,65,66,67,68,69,79,78,77
%N Inverse permutation to A003100.
%H Franklin T. Adams-Watters, <a href="/A174025/b174025.txt">Table of n, a(n) for n = 0..10000</a>
%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%o (PARI) inbase(n,b)=local(r);r=[];while(n>0,r=concat([n%b],r);n\=b);r
%o tobase(v,b)=local(r);for(i=1,#v,r=r*b+v[i]);r
%o a(n)=local(v);v=inbase(n,10);for(k=2,#v,if(v[k-1]%2==1,v[k]=9-v[k]));tobase(v,10)
%K base,easy,nonn
%O 0,3
%A _Franklin T. Adams-Watters_, Mar 05 2010