The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A068956 Number of distinct prime factors of n^n - (n-1)^(n-1). 4
 1, 1, 1, 2, 2, 1, 3, 6, 3, 1, 3, 2, 3, 3, 2, 1, 2, 3, 3, 2, 2, 3, 3, 4, 7, 4, 2, 2, 5, 4, 5, 3, 6, 4, 4, 2, 4, 7, 6, 4, 3, 4, 7, 6, 2, 7, 4, 7, 10, 6, 4, 5, 5, 7, 7, 5, 5, 6, 2, 5, 8, 4, 6, 5, 5, 3, 5, 4, 4, 2, 3, 4, 8, 4, 6, 4, 5, 7, 5, 13, 8, 4, 2, 5, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,4 LINKS Table of n, a(n) for n=2..86. FORMULA a(n) = A001221(A007781(n-1)). EXAMPLE A007781(13) = 10809131718965763 = 3 * 61^2 * 968299894201, therefore a(14) = 3. MATHEMATICA Table[ Length[ FactorInteger[n^n - (n - 1)^(n - 1)]], {n, 2, 52}] (* Reinhard Zumkeller *) PrimeNu[#]&/@(#[[2]]-#[[1]]&/@Partition[Table[n^n, {n, 52}], 2, 1] (* Harvey P. Dale, Aug 24 2014 *) CROSSREFS Cf. A001221, A007781, A068957. Sequence in context: A117919 A309106 A160014 * A124842 A134399 A094436 Adjacent sequences: A068953 A068954 A068955 * A068957 A068958 A068959 KEYWORD nonn AUTHOR Reinhard Zumkeller, Mar 11 2002 EXTENSIONS Edited and extended by Robert G. Wilson v, Mar 15 2002 a(53)-a(54) from Alois P. Heinz, May 12 2017 a(55)-a(86) from Amiram Eldar, Feb 06 2020 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 30 18:42 EDT 2023. Contains 365793 sequences. (Running on oeis4.)