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Search: id:A006530
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| A006530 |
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Largest prime dividing n (with a(1)=1).
(Formerly M0428)
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+0
358
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| 1, 2, 3, 2, 5, 3, 7, 2, 3, 5, 11, 3, 13, 7, 5, 2, 17, 3, 19, 5, 7, 11, 23, 3, 5, 13, 3, 7, 29, 5, 31, 2, 11, 17, 7, 3, 37, 19, 13, 5, 41, 7, 43, 11, 5, 23, 47, 3, 7, 5, 17, 13, 53, 3, 11, 7, 19, 29, 59, 5, 61, 31, 7, 2, 13, 11, 67, 17, 23, 7, 71, 3, 73, 37, 5, 19, 11, 13, 79, 5, 3, 41, 83, 7, 17, 43
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 844.
Handbook of Number Theory, D. S. Mitrinovic et al., Kluwer, Section IV.1.
H. L. Montgomery, Ten Lectures on the Interface Between Analytic Number Theory and Harmonic Analysis, Amer. Math. Soc., 1996, p. 210.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Daniel Forgues, Table of n, a(n) for n=1..100000
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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MAPLE
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with(numtheory, divisors); A006530 := proc(n) local i, t1, t2, t3, t4, t5; t1 := divisors(n); t2 := convert(t1, list); t3 := sort(t2); t4 := nops(t3); t5 := 1; for i from 1 to t4 do if isprime(t3[t4+1-i]) then RETURN(t3[t4+1-i]); fi; od; 1; end;
with(numtheory): a:=proc(n) local u: if n=1 then 1 else u:=factorset(n): max(seq(u[j], j=1..nops(u))) end if end proc: seq(a(n), n=1..90); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 30 2008
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MATHEMATICA
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Prepend[Table[FactorInteger[n][[ -1, 1]], {n, 2, 100}], 1] (Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 12 2005)
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PROGRAM
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(PARI) for(n=1, 100, print1(vecmax(component(factor(n), 1)), ", "))
(MAGMA) [ #f eq 0 select 1 else f[ #f][1] where f is Factorization(n): n in [1..86] ] [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Oct 23 2008]
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CROSSREFS
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Cf. A020639, A006530, A034684, A028233, A034699, A053585. See also A052126, A070087, A070089, A061395.
Sequence in context: A090662 A088387 A162325 this_sequence A102095 A109395 A145254
Adjacent sequences: A006527 A006528 A006529 this_sequence A006531 A006532 A006533
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KEYWORD
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nonn,nice,easy,core
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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