I'm trying to understand the formula presented for the sequence A064532 from the OEIS, looks like a recurrence relation with complex numbers:
$a(10i+j) = a(i) + a(j), etc.$
Sorry if its a simple equation, but I wasn't able to understand it.
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1 Answer
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Nothing to do with complex numbers.
Look at the number of holes in each digit
0 1 2 3 4 5 6 7 8 9
1 0 0 0 0 0 1 0 2 1
Now look at the total number of holes when you write the number in the usual way; just take the weighted sum of the digits.
answered Apr 4, 2012 at 16:59
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2$\begingroup$ Edited only to align the table (insert quadruple space before each line). But it looks to me like the digit 9 has one hole, not zero.$$ $$I'm reminded of the GRE question I heard of last week(?): Which of the following shapes is simple connected? (A)a (B)b (C)c (D)d (E)e $\endgroup$ Apr 4, 2012 at 17:55
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$\begingroup$ Yet more evidence that case matters. Gerhard "aSK mE aBOUT sYSTEM dESIGN" Paseman, 2012.04.04 $\endgroup$ Apr 5, 2012 at 4:22