Three new factors of Fermat numbers

We report the discovery of a new factor for each of the Fermat numbers F 13 , F 15 , F 16 These new factors have 27, 33 and 27 decimal digits respectively. Each factor was found by the elliptic curve method. After division by the new factors and previously known factors, the remaining cofactors are seen to be composite numbers with 2391, 9808 and 19694 decimal digits respectively.

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