A095371 Number of distinct prime factors of record setting repunits (A328899).

0, 1, 2, 5, 7, 8, 10, 13, 14, 20, 21, 22, 26, 29, 32, 33, 34, 35, 40, 44, 55, 56, 63

Offset: 1

Author

Labos Elemer, Jun 04 2004

Keywords

• nonn
• more
• base
• hard

Comments

Conjecture: a(24) = 73, a(25) = 94, a(26) = 99, a(27) >= 107, a(28) >= 127, a(29) >= 136, a(30) >= 140, a(31) >= 151, a(32) >= 159, a(33) >= 163, a(34) >= 178, a(35) >= 184, a(36) >= 213, a(37) >= 214. - Chai Wah Wu, Nov 01 2019

Crossrefs

Cf. A067063, A003020, A001221, A002275, A095370, A004023.

Programs

Mathematica

r[n_] := (10^n-1)/9; L = {}; bst = -1; Do[v = PrimeNu[r[n]]; If[v > bst, bst = v; AppendTo[L, v]], {n, 60}]; L
(* or, based on the b-file of A095370: *)
w = Last /@ Cases[Import["https://oeis.org/A095370/b095370.txt", "Table"], {Integer, _Integer}]; L = {}; bst = -1; Do[ If[j > bst, AppendTo[L, bst = j]], {j, w}]; L (* _Giovanni Resta, Oct 30 2019 *)

Extensions

Data corrected by Ray Chandler and N. J. A. Sloane, May 03 2017

Name edited by Giovanni Resta, Oct 30 2019

a(20)-a(21) from Chai Wah Wu, Oct 30 2019

a(22)-a(23) from Chai Wah Wu, Nov 01 2019