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A332768
a(n) is the greatest prime factor of A180045(n).
1
7, 5, 13, 11, 13, 3, 13, 5, 7, 19, 17, 7, 11, 19, 31, 5, 11, 29, 19, 23, 7, 3, 11, 13, 11, 7, 31, 43, 41, 37, 7, 31, 17, 17, 29, 7, 41, 23, 19, 37, 31, 19, 19, 5, 11, 7, 17, 31, 7, 13, 29, 5, 43, 31, 61, 7, 41, 37, 73, 23, 53, 31, 13, 71, 23, 11, 61, 67, 11
OFFSET
1,1
COMMENTS
Corvaja and Zannier showed that a(n) tends to infinity as n tends to infinity.
LINKS
P. Corvaja and U. Zannier, On the greatest prime factor of (ab+1)(ac+1), arXiv:math/0205136 [math.NT], 2002.
FORMULA
a(n) = A006530(A180045(n)).
EXAMPLE
The first terms, alongside A180045(n), are:
n a(n) A180045(n)
-- ---- --------------
1 7 28 = 7 * 2^2
2 5 45 = 5 * 3^2
3 13 65 = 13 * 5
4 11 66 = 11 * 3 * 2
5 13 91 = 13 * 7
6 3 96 = 3 * 2^5
7 13 117 = 13 * 3^2
8 5 120 = 5 * 3 * 2^3
9 7 126 = 7 * 3^2 * 2
10 19 133 = 19 * 7
PROG
(PARI) See Links section.
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Rémy Sigrist, Feb 23 2020
STATUS
approved