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A170825 a(n) = product of distinct primes of form 6k-1 that divide n. 3
1, 1, 1, 1, 5, 1, 1, 1, 1, 5, 11, 1, 1, 1, 5, 1, 17, 1, 1, 5, 1, 11, 23, 1, 5, 1, 1, 1, 29, 5, 1, 1, 11, 17, 5, 1, 1, 1, 1, 5, 41, 1, 1, 11, 5, 23, 47, 1, 1, 5, 17, 1, 53, 1, 55, 1, 1, 29, 59, 5, 1, 1, 1, 1, 5, 11, 1, 17, 23, 5, 71, 1, 1, 1, 5, 1, 11, 1, 1, 5, 1, 41, 83, 1, 85, 1, 29, 11, 89, 5, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..91.

MAPLE

A170825 := proc(n) a := 1 ; for p in numtheory[factorset](n) do if p mod 6 = 5 then a := a*p ; end if ; end do ; a ; end proc: seq(A170825(n), n=1..120) ; [From R. J. Mathar, Jan 21 2010]

MATHEMATICA

Table[Times@@Select[Transpose[FactorInteger[n]][[1]], IntegerQ[(#+1)/6]&], {n, 100}] (* Harvey P. Dale, Nov 01 2013 *)

CROSSREFS

Cf. A007528, A170819.

Cf. A140214. [From R. J. Mathar, Jan 21 2010]

Sequence in context: A170817 A170818 A046622 * A140214 A071020 A046601

Adjacent sequences:  A170822 A170823 A170824 * A170826 A170827 A170828

KEYWORD

nonn,mult

AUTHOR

N. J. A. Sloane, Dec 25 2009, following a suggestion from Jonathan Vos Post.

EXTENSIONS

More terms from R. J. Mathar, Jan 21 2010

STATUS

approved

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Last modified May 30 00:42 EDT 2017. Contains 287304 sequences.