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A353735
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Number of n-digit terms in A333369.
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6
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5, 24, 130, 792, 5080, 34584, 247360, 1817112, 13918720, 108848664, 869866240, 7169995032, 59085276160, 505735077144, 4311229112320, 37428004374552, 335520388710400, 2861870689152024, 27669446179225600, 223578655251963672, 2398913308953149440, 17708639883984065304
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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Also the number of n-digit simbers, where a simber is a positive integer in which any odd digit, if present, occurs an odd number of times, and any even digit, if present, occurs an even number of times.
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LINKS
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FORMULA
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Conjecture 1: lim_{n->oo} a(2n+1)/a(2n-1) = 100.
Conjecture 2: lim_{n->oo} a(2n+2)/a(2n) = 81. (End)
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EXAMPLE
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There are five 1-digit terms in A333369: 1, 3, 5, 7, 9. Thus, a(1) = 5.
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PROG
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(Python)
def isA333369(n):
digits = list(map(int, str(n)))
return all(digits.count(d)%2 == d%2 for d in set(digits))
def a(n): return sum(1 for i in range(10**(n-1), 10**n) if isA333369(i))
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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