A299978 - OEIS

%I #5 Feb 23 2018 09:48:42

%S 1,7,11,17,21,27,31,37,41,39,9,19,29,49,32,6,2,16,12,26,22,36,42,38,

%T 10,8,20,18,30,28,40,43,5,3,15,13,25,23,35,33,45,44,4,14,24,34,46,52,

%U 56,62,66,72,76,82,86,92,88,50,48,60,58,70,68,80,78,90,91,47,51,57,61,67,71,77,81,87,93,55,53,65,63,75,73,85,83,95,89,59,69,79,99

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

%C A permutation of the positive integers.

%o (PARI) a(n,f=1,d=8,a=1,u=[a])={for(n=2,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. A299988 (analog with nonnegative terms), A299957 (analog with digit 1), A299971, A299972, ..., A299979 (digit 0, 2, ..., 9).

%K nonn,base

%O 1,2

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