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A177892
The number of distinct prime factors in Lucas-Lehmer number A003010(n).
1
1, 2, 2, 3, 2, 3, 6, 3, 5, 5
OFFSET
0,2
COMMENTS
a(10)>2: results from www.factordb.com. - R. J. Mathar, Dec 15 2010
a(11)=4, factorization added to www.factordb.com. - Sean A. Irvine, Mar 25 2011
FORMULA
a(n) = A001221(A003010(n)).
MATHEMATICA
Table[PrimeNu[Ceiling[(2 + Sqrt[3])^(2^n)]], {n, 0, 5}] (* G. C. Greubel, May 16 2017 *)
PROG
(PARI) a=4; until(a=a^2-2, print1(omega(a)", ")) \\ M. F. Hasler, Dec 14 2010
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
G. L. Honaker, Jr., Dec 14 2010
EXTENSIONS
a(9) from Wang Runsen, Oct 26 2020
STATUS
approved