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A068957
Number of prime divisors of n^n - (n-1)^(n-1), counted with multiplicity.
2
1, 1, 1, 2, 2, 1, 4, 6, 3, 1, 3, 2, 4, 3, 2, 1, 2, 3, 4, 2, 2, 3, 3, 4, 9, 4, 2, 2, 5, 4, 6, 3, 6, 4, 4, 2, 6, 7, 6, 4, 3, 4, 8, 6, 2, 7, 4, 7, 12, 6, 4, 5, 5, 7, 9, 5, 5, 6, 2, 5, 10, 4, 6, 5, 5, 3, 9, 4, 4, 2, 3, 4, 9, 4, 6, 4, 5, 7, 9, 13, 8, 4, 2, 5, 7
OFFSET
2,4
FORMULA
a(n) = A001222(A007781(n)).
EXAMPLE
A007781(14) = 10809131718965763 = 3 * 61^2 * 968299894201, therefore a(14) = 4.
MATHEMATICA
Table[ Apply[ Plus, Transpose[ FactorInteger[n^n - (n - 1)^(n - 1)]] [[ -1]]], {n, 2, 52}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Mar 11 2002
EXTENSIONS
Edited and extended by Robert G. Wilson v, Mar 15 2002
a(53)-a(86) from Amiram Eldar, Feb 06 2020
STATUS
approved