A212332 The difference between the largest and smallest prime factor of n as n runs through the numbers with at least two distinct prime factors.

1, 3, 1, 5, 2, 1, 3, 4, 9, 1, 11, 5, 3, 8, 15, 2, 1, 17, 10, 3, 5, 9, 2, 21, 1, 3, 14, 11, 1, 6, 5, 16, 27, 3, 29, 4, 8, 9, 15, 20, 5, 1, 35, 2, 17, 4, 11, 3, 39, 5, 12, 41, 26, 9, 3, 6, 21, 28, 45, 14, 1, 5, 8, 3, 15, 11, 4, 51, 1, 9, 34, 5, 17, 18, 27, 10

Offset

1,2

Comments

a(n) = A100576(n) if A168638(n) contains only two prime distinct divisors.

Nonzero entries of A046665 in the order of appearance. R. J. Mathar, Aug 07 2012

Links

Michel Lagneau, Table of n, a(n) for n = 1..10000

Example

a(13) = 3 because A168638(13) = 30 = 2*3*5 and 5-2 = 3.

Maple

for n from 2 to 200 do
    gpf := A006530(n) ;
    spf := A020639(n) ;
    if gpf <> spf then
        printf("%d, ", gpf-spf) ;
    end if;
end do: # R. J. Mathar, Aug 07 2012

Crossrefs

Cf. A100576, A168638.

Sequence in context: A083722 A111426 A100576 * A371750 A131032 A130323

Adjacent sequences: A212329 A212330 A212331 * A212333 A212334 A212335

Keyword

nonn

Author

Michel Lagneau, Aug 07 2012

Status

approved