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%I #12 Jun 11 2019 11:49:45
%S 0,0,1,1,1,4,1,1,1,7,9,10,11,6,5,4,3,16,17,24,19,23,7,5,9,9,35,4,19,
%T 15,29,12,31,2,17,24,31,23,7,42,39,10,23,42,51,24,37,38,39,14,9,34,51,
%U 15,15,59,59,5,27,37,59,27,13,56,15,44,49,0,59,43,69,23
%N a(n) is the least integer such that concat(a(0), a(1), ..., a(n-1), a(n)) == n-1 (mod n), with a(0) = 0.
%C For any starting value of a(0), a(1)=0 and a(2)=1.
%C First terms with 1, 2, 3, 4 and 5 digits are a(0)=0, a(11)=10, a(98)=157, a(940)=1739 and a(9044)=18963.
%H Paolo P. Lava, <a href="/A308552/b308552.txt">Table of n, a(n) for n = 0..1000</a>
%e a(0) = 0 by definition;
%e a(1) = 0 because 0 mod 1 = 0;
%e a(2) = 1 because 1 mod 2 = 1;
%e a(3) = 1 because 11 mod 3 = 2;
%e a(4) = 1 because 111 mod 4 = 3;
%e a(5) = 4 because 1114 mod 5 = 4; etc.
%p P:=proc(q) local a,b,c,k,n; c:=[]; a:=0;
%p for k from 1 to 71 do for n from 0 to q do
%p b:=a*10^length(convert(n,string))+n:
%p if (b mod k)=k-1 then a:=b; c:=[op(c),n]; break;
%p fi; od; od; 0,op(c); end: P(10^5);
%K nonn,base,easy
%O 0,6
%A _Paolo P. Lava_, Jun 07 2019
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