A139092 a(n) = number of distinct prime divisors of (9+prime(n)!)/9.

3, 3, 2, 2, 2, 3, 2, 3, 4, 4, 5, 3, 3, 6, 5, 2, 3, 4, 3, 3, 4, 4, 4, 3, 7, 3, 3

Offset

4,1

Comments

Conjecture: all prime divisors in A139089 are distinct

a(31) >= 4. - Amiram Eldar, Feb 13 2020

Links

Table of n, a(n) for n=4..30.

FactorDB, Status of a(31) = (9+127!)/9.

Formula

a(n) = A001221(A139089(n)). - Amiram Eldar, Feb 13 2020

Mathematica

a = {}; Do[w = (Prime[n]! + 9)/9; AppendTo[a, w], {n, 4, 16}]; a
PrimeNu[(9+Prime[Range[4, 25]]!)/9] (* Harvey P. Dale, Jul 25 2019 *)

Crossrefs

Cf. A082672, A089085, A089130, A117141, A007749, A139056-A139066, A020458, A139068, A137390, A139070-A139075, A136019, A136020, A136026, A136027, A139089-A139092.

Sequence in context: A133884 A065775 A096837 * A366424 A374409 A021305

Adjacent sequences: A139089 A139090 A139091 * A139093 A139094 A139095

Keyword

nonn,more

Author

Artur Jasinski, Apr 08 2008

Extensions

More terms from Jon E. Schoenfield, Jul 16 2010

a(23)-a(30) using factordb.com from Amiram Eldar, Feb 13 2020

Status

approved