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A143146 a(n) is the smallest positive multiple of n that has the same number of 0's as 1's in its binary representation. 2
2, 2, 9, 12, 10, 12, 35, 56, 9, 10, 44, 12, 52, 42, 135, 240, 153, 180, 38, 180, 42, 44, 184, 216, 50, 52, 135, 56, 232, 150, 527, 992, 165, 170, 35, 180, 37, 38, 156, 240, 41, 42, 172, 44, 135, 184, 141, 240, 49, 50, 153, 52, 212, 216, 165, 56, 228, 232, 177, 180 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

For n = 7, checking: 7*1 = 7 = 111_2; 7*2 = 14 = 1110_2; 7*3 = 21 = 10101_2; 7*4 = 28 = 11100_2. All of these have two many 1's in binary. But 7*5 = 35 = 100011_2, which has both three 0's and three 1's. So a(7) = 35.

MAPLE

a:=proc(n) local b, k: b:=proc(m) convert(m, base, 2) end proc: for k while add(b(k*n)[j], j=1..nops(b(k*n))) <> nops(b(k*n))-add(b(k*n)[j], j=1..nops(b(k*n))) do end do: k*n end proc: seq(a(n), n=1..60); # Emeric Deutsch, Aug 16 2008

MATHEMATICA

spm[n_]:=Module[{k=1}, While[DigitCount[k*n, 2, 0]!=DigitCount[k*n, 2, 1], k++]; k*n]; Array[spm, 60] (* Harvey P. Dale, Apr 25 2014 *)

CROSSREFS

Cf. A031443, A143147.

Sequence in context: A225465 A248665 A066324 * A298663 A325936 A185755

Adjacent sequences:  A143143 A143144 A143145 * A143147 A143148 A143149

KEYWORD

base,nonn

AUTHOR

Leroy Quet, Jul 27 2008

EXTENSIONS

More terms from Emeric Deutsch, Aug 16 2008

STATUS

approved

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Last modified April 17 11:26 EDT 2021. Contains 343064 sequences. (Running on oeis4.)