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%I #12 Sep 14 2020 20:19:56
%S 1,10,21,309,2108,21996,220884,2111105,21866660
%N a(n) is the smallest positive number that is the sum of no fewer than n distinct repdigits.
%C Conjecture: the sequence is infinite.
%e 10 is the sum of 2 distinct repdigits: 9 + 1
%e 21 is the sum of 3 distinct repdigits: 11 + 9 + 1
%e 309 is the sum of 4 distinct repdigits: 222 + 77 + 9 + 1
%e 2108 is the sum of 5 distinct repdigits: 1111 + 888 + 99 + 9 + 1
%e All numbers less than 10 can be summed with less than 2 distinct repdigits.
%e All numbers less than 21 can be summed with less than 3 distinct repdigits.
%Y Cf. A010785, A336748.
%K nonn,base,more
%O 1,2
%A _Falcon Shapiro_, Aug 03 2020
%E a(7)-a(9) from _Sean A. Irvine_, Aug 29 2020