A093221 - OEIS

%I #5 Mar 30 2012 18:39:52

%S 0,8421,75672,760273087,7677679779737737,99997899997,

%T 777300377790097776006777,7777778477777721777777,

%U 77777752577777725277777752,7777770021777777008477777700

%N a(n) is the largest number such that all of a(n)'s length-n substrings are distinct and divisible by 21.

%H Hans Havermann, <a href="/A093211/a093211.txt">Table of A093211-A093299</a>

%e a(2) is 8421 because its length-2 substrings (84, 42, 21) are all distinct and divisible by 21 and there is no larger number with this property

%Y Cf. A093211, A093212, ..., A093299.

%K base,nonn

%O 1,2

%A _Hans Havermann_, Mar 28 2004