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Number of nonnegative integers with property that their base 9/2 expansion (see A024650) has n digits.
0

%I #10 Jul 22 2014 20:12:23

%S 9,36,162,729,3276,14742,66339,298530,1343385,6045228,27203526,

%T 122415867,550871406,2478921327,11155145967,50198156856,225891705852,

%U 1016512676334,4574307043503,20584381695759,92629717630920,416833729339140,1875751782026130

%N Number of nonnegative integers with property that their base 9/2 expansion (see A024650) has n digits.

%e The numbers 9-44 are represented by 20, 21, 22, 23, 24, 25, 26, 27, 28, 40, 41, 42, 43, 44, 45, 46, 47, 48, 60, 61, 62, 63, 64, 65, 66, 67, 68, 80, 81, 82, 83, 84, 85, 86, 87, 88 respectively in base 9/2. These are the only integers with two digits, and so a(2)=36.

%o (Sage)

%o A=[1]

%o for i in [1..60]:

%o A.append(ceil((9-2)/2*sum(A)))

%o [9*x for x in A]

%Y Cf. A024650, A081848.

%K nonn,base

%O 1,1

%A _James Van Alstine_, Jul 21 2014