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A089048
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Number of ways of writing n as a sum of exactly 3 powers of 2.
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3
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0, 0, 0, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 0, 1, 1, 2, 1, 2, 1, 1, 0, 2, 1, 1, 0, 1, 0, 0, 0, 1, 1, 2, 1, 2, 1, 1, 0, 2, 1, 1, 0, 1, 0, 0, 0, 2, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 1, 2, 1, 1, 0, 2, 1, 1, 0, 1, 0, 0, 0, 2, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 2, 1, 1, 0, 1, 0, 0, 0, 1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,7
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COMMENTS
| The powers do not need to be distinct.
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FORMULA
| For n>2: a(n) = (1 + (1 - A000120(n) mod 2)*(1 - n mod 2)) * 0^floor(A000120(n)/4). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 14 2003
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MAPLE
| f := proc(n, k) option remember; if k > n then RETURN(0); fi; if k= 0 then if n=0 then RETURN(1) else RETURN(0); fi; fi; if n mod 2 = 1 then RETURN(f(n-1, k-1)); fi; f(n-1, k-1)+f(n/2, k); end; # present sequence is f(n, 3)
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CROSSREFS
| A column of A089052. Cf. A036987, A075897, A089049, A089050, A089051, A089053.
Sequence in context: A154844 A133831 A066955 * A184348 A192393 A184303
Adjacent sequences: A089045 A089046 A089047 * A089049 A089050 A089051
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Dec 03 2003
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