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Lexicographic first sequence of nonnegative integers such that a(n) + a(n+1) has a digit 8, and no term occurs twice.
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%I #6 Feb 23 2018 09:49:29

%S 0,8,10,18,20,28,30,38,40,41,7,1,17,11,27,21,37,31,47,33,5,3,15,13,25,

%T 23,35,43,39,9,19,29,49,32,6,2,16,12,26,22,36,42,44,4,14,24,34,46,52,

%U 56,62,66,72,76,82,86,92,88,50,48,60,58,70,68,80,78,90,91,57,51,67,61,77,71,87,81,97,83,45,53,55,63,65,73,75,93,85,95,89,59,69

%N Lexicographic first sequence of nonnegative integers such that a(n) + a(n+1) has a digit 8, and no term occurs twice.

%C A permutation of the nonnegative integers.

%o (PARI) a(n,f=1,d=8,a=0,u=[a])={for(n=1,n,f&&if(f==1,print1(a","),write(f,n-1," "a));for(k=u[1]+1,oo,setsearch(u,k)&&next;setsearch(Set(digits(a+k)),d)&&(a=k)&&break);u=setunion(u,[a]);u[2]==u[1]+1&&u=u[^1]);a}

%Y Cf. A299978 (analog with positive terms), A299957 (analog with digit 1), A299970, A299982..A299987, A299969 (digit 0, 2..7, 9).

%K nonn,base

%O 0,2

%A _M. F. Hasler_ and _Eric Angelini_, Feb 22 2018