A177876 a(n) is the number of distinct prime factors in Lucas-Lehmer numbers A003010(k-2)/(2^k-1), where k = A000043(n+1).

2, 3, 3, 4

Offset: 1

Author

G. L. Honaker, Jr., Dec 13 2010

Keywords

• nonn
• hard
• bref
• more

Comments

a(5) of this sequence will require the factorization of A003010(15), an 18742-digit integer divisible by 2^17-1.

Examples

			a(1)=2 because A003010(1)=14, contains exactly 2 distinct prime factors;
a(2)=3 because A003010(3)=37634, contains exactly 3 distinct prime factors;
a(3)=3 because A003010(5)=2005956546822746114, contains exactly 3 distinct prime factors;
a(4)=4 because A003010(11)=the associated 1172-digit Lucas-Lehmer number, contains exactly 4 distinct prime factors.
		

Crossrefs

Cf. A000040, A000668, A003010, A177874, A177875, A177879, A177892

Extensions

Definition corrected by Max Alekseyev, Jul 29 2024