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A064891
"Binary potency" of n: length of shortest blocks of 0's inserted between the bits of n required to "dilute" it into a nonprime.
3
0, 1, 2, 0, 2, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 2, 0, 1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 3, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 3, 0, 0, 0, 3, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 1, 0, 3, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0
OFFSET
1,3
COMMENTS
Zero for all nonprime n. Note that the +2 dilution of 3 is not the +1 dilution of 5!
EXAMPLE
3 = 11 -> 0101 = 5 -> 001001 = 9, so a(3) = 2; 5 = 101 -> 010001 = 17 -> 001000001 = 65, so a(5) = 2
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Marc LeBrun, Oct 10 2001
STATUS
approved