A001916  Primes p such that the congruence 2^x = 5 (mod p) is solvable.

(That is, primes p such that 5 is a power of 2, modulo p.  Or primes p such that
5 is in the group generated by 2 modulo p.)

For terms of the sequence less than 10^6, the number
that fall into each residue class modulo m are as follows:

Residue counts:
2   [0, 44357]
3   [0, 19281, 25076]
4   [0, 20957, 0, 23400]
5   [0, 12682, 8253, 8264, 15158]
6   [0, 19281, 0, 0, 0, 25076]
7   [0, 6614, 7571, 7561, 7518, 7510, 7583]
8   [0, 5104, 0, 15775, 0, 15853, 0, 7625]
9   [0, 6271, 8370, 0, 6530, 8298, 0, 6480, 8408]
10   [0, 12682, 0, 8264, 0, 0, 0, 8253, 0, 15158]
11   [1, 4072, 4515, 4459, 4457, 4496, 4478, 4523, 4441, 4436, 4479]
12   [0, 9120, 0, 0, 0, 11837, 0, 10161, 0, 0, 0, 13239]

Unlike the primes sequence, the distributions here are not uniform
in the relatively prime residue classes. For example, primes in this
sequence are markedly more likely to be congruent to 2 (mod 3) than
to 1 (mod 3).  

Strong spectral lines at 44100/6 (7350 hz), 44100/8 (about 5500 hz), 44100/10 (4410 hz),
similar to the primes sequence.

- Nidhi Vora