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A141552 Transformed products of prime factors of the composites, the largest prime and smallest prime incremented by 1. 0
9, 12, 18, 16, 18, 24, 24, 24, 36, 36, 36, 32, 36, 48, 36, 42, 48, 48, 54, 72, 48, 54, 48, 72, 60, 56, 72, 72, 72, 72, 72, 96, 64, 90, 72, 84, 108, 72, 96, 80, 90, 108, 96, 96, 144, 84, 108, 108, 96, 120, 144, 114, 120, 120, 96, 126, 144, 144, 126, 144, 108, 132, 120, 144 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

In the prime number decomposition of k=A002808(i), i=1,2,3,.., one instance of the largest prime, pmax=A052369(i), is replaced by pmax+1 and one instance of the smallest prime, pmin=A056608(i), is replaced by pmin+1. The product of this modified list of factors, k*(pmax+1)*(pmin+1)/(pmin*pmax), is added to the sequence.

LINKS

Table of n, a(n) for n=1..64.

EXAMPLE

k(1)=4=(p(max)=2)*(p(min)=2), transformed (2+1)*(2+1)=3*3=9=a(1).

k(2)=6=(p(max)=3)*(p(min)=2), transformed (3+1)*(2+1)=4*3=12=a(2).

k(6)=12=(p(max)=3)*(p=2)*(p(min)=2), transformed (3+1)*2*(2+1)=4*2*3=24=a(6), etc.

CROSSREFS

Cf. A141218, A141219, A141220, A141284.

Sequence in context: A154631 A199593 A174525 * A317720 A162822 A087269

Adjacent sequences:  A141549 A141550 A141551 * A141553 A141554 A141555

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Aug 14 2008

EXTENSIONS

Edited and corrected by R. J. Mathar, Aug 18 2008

STATUS

approved

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Last modified October 19 04:40 EDT 2019. Contains 328211 sequences. (Running on oeis4.)