A177892 The number of distinct prime factors in Lucas-Lehmer number A003010(n).

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

Links

Table of n, a(n) for n=0..9.

Dario Alejandro Alpern, Factorization using the Elliptic Curve Method (along with sigma_0, sigma_1 and phi functions)

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

Cf. A001221, A003010, A177876.

Sequence in context: A056160 A106245 A129568 * A341758 A236433 A117122

Adjacent sequences: A177889 A177890 A177891 * A177893 A177894 A177895

Keyword

nonn,hard,more

Author

G. L. Honaker, Jr., Dec 14 2010

Extensions

a(9) from Wang Runsen, Oct 26 2020

Status

approved