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A084127 Prime factor >= other prime factor of n-th semiprime. 29
2, 3, 3, 5, 7, 5, 7, 11, 5, 13, 11, 17, 7, 19, 13, 23, 7, 17, 11, 19, 29, 31, 13, 23, 37, 11, 41, 17, 43, 29, 13, 31, 47, 19, 53, 37, 23, 59, 17, 11, 61, 41, 43, 19, 67, 47, 71, 13, 29, 73, 31, 79, 53, 23, 83, 13, 59, 89, 61, 37, 17, 97, 67, 101, 29, 41, 103, 19, 71, 107, 43, 31 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n)=A006530(A001358(n))=n/A020639(A001358(n)); A001358(n)=A084126(n)*a(n).

Largest nontrivial divisor of n-th semiprime. [From Juri-Stepan Gerasimov, Apr 18 2010]

LINKS

Zak Seidov, Table of n, a(n) for n = 1..1000

Eric Weisstein's World of Mathematics, Semiprime

PROG

(Haskell)

a084127 = a006530 . a001358  -- Reinhard Zumkeller, Nov 25 2012

(PARI) lista(nn) = {for (n=2, nn, if (bigomega(n)==2, f = factor(n); print1(f[length(f~), 1], ", ")); ); } \\ Michel Marcus, Jun 05 2013

CROSSREFS

Cf. A014673, A061299, A068318, A087718, A087794, A089994, A089995, A096932, A106550, A106554, A108542, A126663, A131284, A138510, A138511. current versions:.

Sequence in context: A066072 A239586 A180611 * A089934 A113460 A113470

Adjacent sequences:  A084124 A084125 A084126 * A084128 A084129 A084130

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, May 15 2003

EXTENSIONS

Corrected by T. D. Noe, Nov 15 2006

STATUS

approved

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Last modified May 29 15:34 EDT 2020. Contains 334700 sequences. (Running on oeis4.)