A141219 - OEIS

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A141219

Write the n-th nonprime (A018252(n)) as a product of primes; increase one copy of the largest prime by 1 and decrease one copy of the smallest prime by 1, multiply the resulting numbers.

1, 3, 4, 6, 8, 6, 8, 8, 12, 12, 12, 12, 16, 12, 16, 24, 14, 24, 16, 18, 24, 24, 18, 32, 24, 20, 28, 24, 24, 24, 36, 24, 32, 48, 30, 36, 28, 36, 48, 32, 40, 30, 36, 32, 48, 48, 56, 36, 36, 48, 40, 48, 38, 60, 40, 72, 42, 48, 72, 42, 48, 72, 44, 60, 48, 54, 84

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..67.

EXAMPLE

1st nonprime = 1 (has no prime factors); a(1) = empty product = 1.

2nd nonprime = 4 = (p(max)=2)*(p(min)=2); a(2) = (2+1)*(2-1) = 3*1 = 3.

3rd nonprime = 6 = (p(max)=3)*(p(min)=2); a(3) = (3+1)*(2-1) = 4*1 = 4.

4th nonprime = 8 = (p(max)=2)*(p=2)*(p(min)=2); a(4) = (2+1)*2*(2-1) = 3*2*1 = 6.

CROSSREFS

Sequence in context: A290115 A225794 A206769 * A069211 A368152 A242822