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A057935
Number of prime factors of 9^n + 1 (counted with multiplicity).
18
2, 2, 3, 3, 4, 3, 4, 2, 4, 3, 4, 6, 4, 4, 6, 2, 4, 4, 4, 5, 7, 5, 4, 4, 8, 4, 5, 6, 4, 7, 5, 2, 6, 5, 9, 8, 5, 6, 7, 5, 5, 10, 7, 6, 9, 4, 4, 6, 9, 6, 8, 7, 6, 9, 8, 9, 9, 5, 3, 11, 6, 4, 11, 6, 8, 9, 9, 8, 6, 9, 5, 6, 6, 6, 13, 4, 8, 7, 5, 4, 7, 6, 5, 11, 8, 5, 8, 7, 4, 11, 7, 9, 9, 5, 9, 7, 5, 6, 10, 7, 6
OFFSET
1,1
LINKS
Max Alekseyev, Table of n, a(n) for n = 1..345 (first 329 terms from Amiram Eldar)
S. S. Wagstaff, Jr., The Cunningham Project
FORMULA
a(n) = A057952(2n) - A057952(n). - T. D. Noe, Jun 19 2003
a(n) = A001222(A062396(n)) = A057941(2*n). - Amiram Eldar, Feb 02 2020
MATHEMATICA
PrimeOmega[Table[9^n + 1, {n, 1, 30}]] (* Amiram Eldar, Feb 02 2020 *)
PROG
(Magma) f:=func<n|&+[p[2]: p in Factorization(n)]>; [f(9^n + 1):n in [1..100]]; // Marius A. Burtea, Feb 02 2020
CROSSREFS
bigomega(b^n+1): A057934 (b=10), this sequence (b=9), A057936 (b=8), A057937 (b=7), A057938 (b=6), A057939 (b=5), A057940 (b=4), A057941 (b=3), A054992 (b=2).
Sequence in context: A324863 A332894 A269989 * A292042 A282715 A124831
KEYWORD
nonn
AUTHOR
Patrick De Geest, Oct 15 2000
STATUS
approved