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A163178 a(n) is the central prime factor of A046339(n). 1
2, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 5, 2, 3, 3, 2, 5, 2, 5, 2, 3, 2, 2, 7, 3, 3, 5, 3, 5, 2, 3, 2, 3, 2, 2, 5, 2, 5, 3, 7, 2, 3, 7, 3, 2, 5, 2, 5, 3, 2, 3, 5, 2, 3, 7, 3, 2, 5, 2, 5, 2, 3, 2, 2, 3, 5, 7, 2, 7, 11, 3, 2, 7, 3, 3, 5, 3, 3, 2, 7, 2, 3, 2, 7, 5, 3, 2, 3, 2, 5, 11, 2, 5, 2, 3, 2, 5, 2, 2, 3, 2, 7, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..104.

EXAMPLE

a(8)=2 since A046339(8) = 32 = 2*2*2*2*2.

a(9)=3 since A046339(9) = 42 = 2*3*7.

a(10)=2 since A046339(10) = 44 = 2*2*11.

a(11)=3 since A046339(11) = 45 = 3*3*5.

a(12)=2 since A046339(12) = 48 = 2*2*2*2*3.

MAPLE

cpr := proc(n) nred := n ; while numtheory[bigomega](nred) > 1 do pf := sort(convert(numtheory[factorset](nred), list)) ; nred := nred/op(1, pf)/op(-1, pf) ; od: nred ; end:

A046339 := proc(n) option remember ; if n = 1 then 8 ; else for a from procname(n-1)+1 do if not isprime(a) and numtheory[bigomega](a) mod 2 = 1 then RETURN(a) ; fi; od: fi; end:

A163178 := proc(n) cpr(A046339(n)) ; end; seq(A163178(n), n=1..120) ; # R. J. Mathar, Jul 25 2009

CROSSREFS

Cf. A046339, A162361.

Sequence in context: A024677 A276856 A174296 * A219545 A029374 A255933

Adjacent sequences:  A163175 A163176 A163177 * A163179 A163180 A163181

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Jul 22 2009

EXTENSIONS

More terms from R. J. Mathar, Jul 25 2009

STATUS

approved

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Last modified October 1 07:48 EDT 2020. Contains 337442 sequences. (Running on oeis4.)