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A117366
a(n) = smallest prime greater than the largest prime dividing n.
15
2, 3, 5, 3, 7, 5, 11, 3, 5, 7, 13, 5, 17, 11, 7, 3, 19, 5, 23, 7, 11, 13, 29, 5, 7, 17, 5, 11, 31, 7, 37, 3, 13, 19, 11, 5, 41, 23, 17, 7, 43, 11, 47, 13, 7, 29, 53, 5, 11, 7, 19, 17, 59, 5, 13, 11, 23, 31, 61, 7, 67, 37, 11, 3, 17, 13, 71, 19, 29, 11, 73, 5, 79, 41, 7, 23, 13, 17, 83, 7
OFFSET
1,1
LINKS
FORMULA
a(n) = A151800(A006530(n)). - Reinhard Zumkeller, Apr 06 2015
a(n) = A000040(A159081(n)). - Antti Karttunen, Jan 15 2020
EXAMPLE
5 is the largest prime dividing 10. So a(10) is the smallest prime > 5, which is 7.
MATHEMATICA
Table[Prime[PrimePi[FactorInteger[n][[Length[FactorInteger[n]]]][[1]]]+1], {n, 2, 80}], 2, 1] (* Stefan Steinerberger, Apr 09 2006 *)
PROG
(Haskell)
a117366 = a151800 . a006530 -- Reinhard Zumkeller, Apr 06 2015
(PARI) A117366(n) = if(1==n, 2, nextprime(1+vecmax(factor(n)[, 1]))); \\ Antti Karttunen, Jan 15 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Mar 10 2006
EXTENSIONS
More terms from Stefan Steinerberger, Apr 09 2006
STATUS
approved