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A070009 Least number m such that the arithmetic mean of the distinct prime divisors of m is equal to 2^n. 2
2, 15, 39, 87, 183, 2071, 1255, 1527, 3063, 18402, 12279, 106327, 49143, 622231, 589794, 1703767, 1310695, 9961111, 3145719, 31457210, 12582903, 310377127, 50331639, 2046816631, 335544295, 10603194271, 8858369762, 1610612727, 44023413103, 40802188951 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Are there any terms with more than 3 prime factors? - David Wasserman, May 05 2003
LINKS
FORMULA
a(n) = Min{x; A008472(x)/A001221(x)=2^n}.
EXAMPLE
a(15) = 589794 because m = 2*3*98299; mean = (2+3+98299)/3 = 32768 = 2^15.
MATHEMATICA
a = Table[0, {21}]; Do[b = Transpose[ FactorInteger[n]][[1]]; c = Log[2, Apply[ Plus, b] / Length[b]]; If[ IntegerQ[c] && a[[c]] == 0, a[[c]] = n], {n, 2, 10^8/3}]; a
CROSSREFS
Sequence in context: A295367 A214541 A180223 * A070170 A033568 A200156
KEYWORD
nonn
AUTHOR
Labos Elemer, Apr 11 2002
EXTENSIONS
Edited and extended by Robert G. Wilson v, Apr 30 2002
More terms from David Wasserman, May 05 2003
a(29)-a(30) from Donovan Johnson, Aug 06 2012
STATUS
approved

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Last modified March 29 04:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)