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 A089048 Number of ways of writing n as a sum of exactly 3 powers of 2. 3
 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; text; internal format)
 OFFSET 0,7 COMMENTS The powers do not need to be distinct. LINKS FORMULA For n>2: a(n) = (1 + (1 - A000120(n) mod 2)*(1 - n mod 2)) * 0^floor(A000120(n)/4). - Reinhard Zumkeller, Dec 14 2003 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) MATHEMATICA a[n_] := If[n < 3, 0, ((1 - Mod[n, 2])*(1 - Mod[DigitCount[n, 2, 1], 2]) + 1)*If[Floor[(1/4)*DigitCount[n, 2, 1]] == 0, 1, 0]]; Table[a[n], {n, 0, 104}] (* Jean-François Alcover, Feb 13 2018, after Reinhard Zumkeller_ *) CROSSREFS A column of A089052. Cf. A036987, A075897, A089049, A089050, A089051, A089053. Sequence in context: A305054 A238097 A066955 * A263025 A184348 A242481 Adjacent sequences:  A089045 A089046 A089047 * A089049 A089050 A089051 KEYWORD nonn AUTHOR N. J. A. Sloane, Dec 03 2003 STATUS approved

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Last modified August 14 17:44 EDT 2018. Contains 313751 sequences. (Running on oeis4.)