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%I #11 Jul 22 2014 12:34:25
%S 10,10,10,20,30,40,60,80,120,170,240,340,490,700,1000,1430,2040,2910,
%T 4160,5940,8490,12130,17330,24750,35360,50520,72170,103100,147280,
%U 210400,300570,429390,613410,876300,1251860,1788370,2554820,3649740,5213910,7448450
%N Number of nonnegative integers with property that their base 10/7 expansion has n digits.
%C See A024662 for an explanation of base 10/7.
%e a(2) = 10 because 70, 71, 72, 73, 74, 75, 76, 77, 78 and 79 are the base 10/7 expansions for the integers 10, 11, 12, 13, 14, 15, 16, 17, 18 and 19 respectively and these are the only integers with 2 digits.
%o (Sage)
%o A=[1]
%o for i in [1..60]:
%o A.append(ceil(((10-7)/7)*sum(A)))
%o [10*x for x in A]
%Y Cf. A024662, A081848, A245356.
%K nonn,base
%O 1,1
%A _Hailey R. Olafson_, Jul 21 2014