A201649 - OEIS

A201649

The fifth of the five known sets of nine distinct odd numbers the sum of whose reciprocals is 1.

3, 5, 7, 9, 11, 15, 33, 45, 385

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OFFSET

1,1

COMMENTS

John Leech showed that nine is the smallest number of odd numbers with this property.

This set was apparently discovered by S. Yamashita in 1976.

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory (UPINT), Section D11.

LINKS

Nechemia Burshtein, The equation sum(i=1,9,1/xi)=1 in distinct odd integers has only the five known solutions, Journal of Number Theory, Volume 127, Issue 1, November 2007, Pages 136-144.

The Prime Puzzles and Problems Connection, Problem 35

CROSSREFS

There are five known sets of nine odd numbers with this property: A201644, A201646, A201647, A201648, A201649.

KEYWORD

nonn,fini,full

AUTHOR

STATUS

approved