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A333359 Variation of Van Eck's sequence A181391: a(n+1) = the minimum positive offset m from a(n) such that the decimal concatenation of a(n-m), a(n-m+1), ..., a(n-m+k) = a(n), where k >= 0; a(n+1)=0 if no such m exists. Start with a(1)=0.

%I A333359 #15 Mar 16 2020 19:08:03
%S A333359 0,0,1,0,2,0,2,2,1,6,0,5,0,2,6,5,4,0,5,3,0,3,2,9,0,4,9,3,6,14,0,6,3,5,
%T A333359 15,0,5,3,5,2,17,0,6,11,0,3,8,0,3,3,1,42,0,5,15,20,51,0,5,5,1,10,59,0,
%U A333359 6,22,59,4,42,17,29,48,0,9,47,0,3,27,0,3,3,1,21,75,0,6
%N A333359 Variation of Van Eck's sequence A181391: a(n+1) = the minimum positive offset m from a(n) such that the decimal concatenation of a(n-m), a(n-m+1), ..., a(n-m+k) = a(n), where k >= 0; a(n+1)=0 if no such m exists. Start with a(1)=0.
%C A333359 The terms up to a(56) are the same as A181391 but vary from a(57) and beyond. After 10000 terms the smallest number not appearing is 332.
%H A333359 Brady Haran and N. J. A. Sloane, <a href="https://www.youtube.com/watch?v=etMJxB-igrc">Don't Know (the Van Eck Sequence)</a>, Numberphile video (2019).
%e A333359 a(42) = 0 as a(41) = 17, and neither '17' or adjacent sequence terms '1' and '7' appear earlier in the sequence.
%e A333359 a(57) = 51 as a(56) = 20, and the value '20' is the concatenation of a(5) = 2 and a(6) = 0, and a(5) is fifty-one terms back from a(56).
%Y A333359 Cf. A181391, A007908, A001704.
%K A333359 nonn,base
%O A333359 1,5
%A A333359 _Scott R. Shannon_, Mar 16 2020