1,3

Ray Chandler, Table of n, a(n) for n = 1..322

Eric Weisstein's World of Mathematics, Repunit.

a(n) = A001222(A002275(n)). - Ray Chandler, Apr 22 2017

a(n) = A057951(n) - 2. - Ray Chandler, Apr 24 2017

R(6) = 111111 = (3) (7) (11) (13) (37), so a(6) = 5.

Table[PrimeOmega[(10^n - 1)/9], {n, 60}] (* Michael De Vlieger, Apr 29 2015 *)

(PARI) a(n)=bigomega(10^n\9) \\ Charles R Greathouse IV, Apr 29 2015

Cf. A001222, A002275, A057951. For the number of distinct prime factors see A095370.

Sequence in context: A183380 A260587 A095370 * A080348 A096396 A029662

Adjacent sequences: A046050 A046051 A046052 * A046054 A046055 A046056

nonn

Eric W. Weisstein

approved