A174950 Size of sea of semiprimes surrounding n-th prime.
0, 1, 2, 1, 2, 2, 0, 0, 2, 0, 0, 2, 0, 0, 1, 0, 2, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 1, 0, 2, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 2, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 1, 0, 0
Offset: 1
Keywords
Examples
a(1)=0 because first prime is in a sea of 0 semiprimes; a(2)=1 because 2nd prime is in a sea of 1 semiprimes (3, 4); a(3)=2 because 3rd prime is in a sea of 2 semiprimes (4, 5, 6); a(4)=1 because 4th prime is in a sea of 1 semiprimes (6, 7); a(4)=2 because 5th prime is in a sea of 2 semiprimes (9, 10, 11).
Extensions
Corrected by Ray Chandler, Apr 06 2010
Comments