A038888 Primes p such that 15 is not a square mod p. For terms of the sequence less than 10^6, the number that fall into the residue classes modulo m are as follows: 2 [0, 39298] 3 [0, 19695, 19603] 4 [0, 19614, 0, 19684] 5 [0, 9837, 9805, 9848, 9808] 6 [0, 19695, 0, 0, 0, 19603] 7 [0, 6595, 6527, 6578, 6506, 6544, 6548] 8 [0, 9827, 0, 9853, 0, 9787, 0, 9831] 9 [0, 6548, 6559, 0, 6599, 6494, 0, 6548, 6550] 10 [0, 9837, 0, 9848, 0, 0, 0, 9805, 0, 9808] 11 [0, 3968, 3927, 3909, 3916, 3952, 3913, 3951, 3955, 3892, 3915] 12 [0, 9832, 0, 0, 0, 9782, 0, 9863, 0, 0, 0, 9821] Distributions in residue classes is uniform in all classes relatively prime to the modulus. Quite harmonic for a prime sequence. Fundamental frequency at 735Hz (44100/60) with lots of visible harmonic spectral bands but many appear faint. This sound has a prominent spectral component at 44100/60=735 hz that the primes sound does not have; I think this contributes to the noticeable difference between the sound of this sequence and the sound of the primes.