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A057941 Number of prime factors of 3^n + 1 (counted with multiplicity). 17
2, 2, 3, 2, 3, 3, 3, 3, 5, 4, 4, 3, 3, 4, 6, 2, 5, 4, 4, 3, 7, 4, 3, 6, 5, 4, 7, 4, 5, 6, 4, 2, 7, 4, 5, 4, 5, 4, 8, 5, 4, 7, 3, 5, 10, 4, 5, 4, 5, 8, 9, 4, 4, 5, 7, 6, 8, 4, 4, 7, 4, 5, 13, 2, 5, 6, 4, 5, 9, 9, 7, 8, 4, 5, 12, 6, 6, 7, 5, 5, 12, 5, 6, 10, 9, 7, 11, 6, 5, 9, 8, 4, 9, 4, 8, 6, 5, 9, 14, 6, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Max Alekseyev, Table of n, a(n) for n = 1..691 (first 658 terms from Amiram Eldar)
S. S. Wagstaff, Jr., The Cunningham Project
FORMULA
a(n) = A057958(2n) - A057958(n) - T. D. Noe, Jun 19 2003
a(n) = A001222(A034472(n)). - Amiram Eldar, Feb 01 2020
MATHEMATICA
PrimeOmega[3^Range[110]+1] (* Harvey P. Dale, Jun 20 2015 *)
PROG
(PARI) a(n)=bigomega(n^3+1) \\ Charles R Greathouse IV, Sep 14 2015
CROSSREFS
bigomega(b^n+1): A057934 (b=10), A057935 (b=9), A057936 (b=8), A057937 (b=7), A057938 (b=6), A057939 (b=5), A057940 (b=4), this sequence (b=3), A054992 (b=2).
Sequence in context: A076235 A268058 A334686 * A358550 A126071 A338292
KEYWORD
nonn
AUTHOR
Patrick De Geest, Oct 15 2000
STATUS
approved

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Last modified June 15 02:47 EDT 2024. Contains 373402 sequences. (Running on oeis4.)