

A229850


Number of prime factors congruent to 1 mod 3 that divide the Fermat number 2^(2^n) + 1.


4



0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 3, 2
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,11


COMMENTS

a(n) < A046052(n) because all Fermat numbers greater than 3 are equal to 2 (mod 3).
If A046052(n) = 3, then a(n) = 0 or 2.
a(n) <= A228846(n)  n  1 for n = 0 to 11.


REFERENCES

M. Krizek, F. Luca, L. Somer, 17 Lectures on Fermat Numbers: From Number Theory to Geometry, CMS Books in Mathematics, vol. 9, SpringerVerlag, New York, 2001, pp. 6163, 6566.


LINKS



CROSSREFS



KEYWORD

nonn,hard,more


AUTHOR



STATUS

approved



