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%I #9 Jul 27 2024 13:54:44
%S 11,29,47,67,85,105,123,143,161,181,182,184,187,190,193,196,199,202,
%T 205,209,239,266,296,323,353,380,410,445,446,448,451,454,457,460,463,
%U 467,497,527,554,584,614,641,671,701,727,728,730,733,736,739,742,745,748
%N Positive integers not occurring in A167520.
%C Equivalently, positions of zero digits in A167520 (when all terms are concatenated).
%C The first differences are (18, 18, 20, 18, 20, 18, 20, 18, 20, 1, 2, 3, 3, 3, 3, 3, 3, 3, 4, 30, 27, 30, 27, 30, 27, 30, 35, 1, 2, 3, 3, 3, 3, 3, 4, ...)
%e The first occurrence of the digit '0' in A167520 is as the least significant digit of A167520(10)=10, which occurs at position 11, thus a(1)=11. Equivalently, this is the least positive integer missing in A167520.
%e The next occurrence of the digit '0' in A167520 is at position 29 (and 29 is the second positive integer not occurring in A167520), thus a(2)=29.
%o (PARI) base(n,b=10) = { my( a=[ n%b ]); while( 0<n\=b, a=concat( n%b, a )); a }
%o {a=b=[]; for(n=1,499, #b>=n & for(i=a[n-1]+1,#b,b[i] & (a=concat(a,i)) & break); #a<n & a=concat(a,#b+1); b=concat(b,base(a[n]))); for(i=1,#b, b[i] || print1(i","))}
%Y Cf. A167500-A167503, A167520-A167523.
%K nonn,base
%O 1,1
%A _M. F. Hasler_, Nov 05 2009