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 A201643 John Leech's example of a set of eleven distinct odd numbers the sum of whose reciprocals is 1. 22
 3, 5, 7, 9, 15, 21, 27, 35, 63, 105, 135 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS There are smaller sets - see for example A201644. One of 17 possible sets of eleven numbers of the form 3^alpha 5^beta 7^gamma whose sum of reciprocals is 1. The 17 solutions are given in A211118 - A211134. N. J. A. Sloane, Apr 02 2012 REFERENCES R. K. Guy, Unsolved Problems in Number Theory (UPINT), Section D11. LINKS Burshtein, Nechemia. On distinct unit fractions whose sum equals 1. Discrete Math. 5 (1973), 201--206. MR0314738 (47 #3290) Burshtein, Nechemia. All the solutions of the equation Sum_{i=1..11}} 1/x_i = 1 in distinct integers of the form x_i = 3^alpha 5^beta 7^gamma. Discrete Math. 308 (2008), no. 18, 4286--4292. MR2427761 (2009e:11061) The Prime Puzzles and Problems Connection, Problem 35 CROSSREFS Cf. A201643, A201644, A201646, A201647, A201648, A201649. Sequence in context: A211134 A211132 A211131 * A018388 A100866 A327823 Adjacent sequences:  A201640 A201641 A201642 * A201644 A201645 A201646 KEYWORD nonn,fini,full AUTHOR N. J. A. Sloane, Dec 03 2011 STATUS approved

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Last modified December 2 08:19 EST 2021. Contains 349437 sequences. (Running on oeis4.)