

A141554


Transformed nonprime products of prime factors of the composites, the largest prime decremented by 2 and the smallest prime incremented by 2.


1



0, 4, 0, 12, 8, 20, 15, 0, 12, 24, 25, 36, 16, 21, 44, 15, 40, 36, 0, 45, 60, 35, 24, 68, 55, 48, 60, 72, 45, 84, 32, 45, 60, 75, 88, 36, 63, 80, 85, 108, 72, 116, 75, 0, 77, 108, 120, 105, 100, 48, 140, 75, 136, 81, 132, 96, 45, 156, 120, 105, 164, 135, 144, 108, 99, 168
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OFFSET

1,2


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 pmax2 and one instance of the smallest prime, pmin=A056608(i), is replaced by pmin+2. If the product of this modified list of factors, k*(pmax2)*(pmin+2)/(pmin*pmax), is nonprime, it is added to the sequence.


LINKS

Table of n, a(n) for n=1..66.


EXAMPLE

k(1)=4=(p(max)=2)*(p(min)=2), transformed (22)*(2+2)=0*4=0=a(1).
k(2)=6=(p(max)=3)*(p(min)=2), transformed (32)*(2+2)=1*4=4=a(2).
k(3)=8=(p(max)=2)*(p=2)*(p(min)=2), transformed (22)*2*(2+2)=0*2*4=0=a(3).
k(4)=9=(p(max)=3)*(p(min)=3), transformed (32)*(3+2)=1*5=5 (prime, skipped).
k(5)=10=(p(max)=5)*(p(min)=2), transformed (52)*(2+2)=3*4=12=a(4).


CROSSREFS

Cf. A141218, A141219, A141220, A141284.
Sequence in context: A273761 A273424 A273329 * A076600 A002978 A273609
Adjacent sequences: A141551 A141552 A141553 * A141555 A141556 A141557


KEYWORD

nonn


AUTHOR

JuriStepan Gerasimov, Aug 14 2008


EXTENSIONS

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


STATUS

approved



