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
Keywords
Examples
a(13) = 3 because A168638(13) = 30 = 2*3*5 and 5-2 = 3.
Links
- Michel Lagneau, Table of n, a(n) for n = 1..10000
Programs
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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
Comments