OFFSET
1,5
LINKS
Sean A. Irvine, Table of n, a(n) for n = 1..118
Florian Luca and Igor E. Shparlinski, On the largest prime factor of n! + 2^n - 1, Journal de Théorie des Nombres de Bordeaux 17 (2005), 859-870.
Apurva Rai, Python Program for a(81)-a(100)
Apurva Rai, Python program for a(101)-a(105)
FORMULA
MATHEMATICA
a = {}; Do[AppendTo[a, n! + 2 n - 1], {n, 1, 40}]; b = {}; Do[c = Length[FactorInteger[a[[n]]]]; AppendTo[b, c], {n, 1, Length[a]}]; b (* Artur Jasinski *)
PrimeNu @ Table[n! + 2*n - 1, {n, 1, 30}] (* Amiram Eldar, Feb 05 2020 *)
PROG
(PARI) a(n)=omega(n!+2*n-1) \\ Charles R Greathouse IV, Feb 01 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Apr 22 2008
EXTENSIONS
a(41)-a(60) from Amiram Eldar, Feb 05 2020
a(61)-a(80) from Jinyuan Wang, Apr 03 2020
a(81)-a(100) from Apurva Rai, Sep 20 2020
a(101)-a(105) from Apurva Rai, Sep 21 2020
STATUS
approved