A276983: Semiprimes n such that n-1 or n+1 is prime.

Crunchy noise. Medium-pitch. 

Residue counts:
2   [8622, 0]
3   [1, 4323, 4298]
4   [1, 0, 8621, 0]
5   [1, 1421, 2884, 2872, 1444]
6   [1, 0, 4298, 0, 4323, 0]
7   [1, 853, 1710, 1735, 1742, 1723, 858]
8   [0, 0, 4254, 0, 1, 0, 4367, 0]
9   [0, 1468, 1423, 0, 1409, 1440, 1, 1446, 1435]
10   [1, 0, 2884, 0, 1444, 0, 1421, 0, 2872, 0]
11   [1, 477, 961, 963, 955, 940, 978, 971, 944, 955, 477]
12   [0, 0, 4298, 0, 1, 0, 1, 0, 0, 0, 4322, 0]

Density information:
A(x) at x=10,100,1000,...:
[3, 11, 44, 222, 1340, 8622]

A(x)/x at x=10,100,1000,...:
0.3,0.11,0.044,0.0222,0.0134,0.008622,

First 100 first differences:
[2, 4, 4, 8, 16, 8, 12, 4, 12, 8, 24, 52, 8, 12, 16, 32, 36, 16, 36, 32, 12, 
 24, 16, 24, 36, 8, 12, 24, 40, 20, 24, 28, 48, 12, 44, 16, 24, 80, 24, 16, 8, 
 96, 16, 20, 76, 60, 32, 16, 12, 24, 44, 24, 12, 4, 44, 16, 56, 16, 32, 36, 96,
 4, 36, 96, 68, 52, 32, 28, 60, 24, 8, 12, 24, 36, 40, 68, 136, 104, 12, 16, 84, 
 20, 16, 204, 20, 40, 20, 24, 16, 44, 36, 24, 40, 56, 48, 36, 16, 36, 60, 152]

First 99 second differences:
[2,0,4,8,-8,4,-8,8,-4,16,28,-44,4,4,16,4,-20,20,-4,-20,12,-8,8,12,-28,4,12,16,
 -20,4,4,20,-36,32,-28,8,56,-56,-8,-8,88,-80,4,56,-16,-28,-16,-4,12,20,-20,-12,
 -8,40,-28,40,-40,16,4,60,-92,32,60,-28,-16,-20,-4,32,-36,-16,4,12,12,4,28,68,
 -32,-92,4,68,-64,-4,188,-184,20,-20,4,-8,28,-8,-12,16,16,-8,-12,-20,20,24,92]

The most distinct line is at 11025Hz which corresponds to 44100/4.


-- David Oh