A023200: Primes p such that p + 4 is also prime. Very crackly and consistently noisy throughout. Residue counts: 2 [0, 8144] 3 [1, 8143, 0] 4 [0, 4003, 0, 4141] 5 [0, 0, 2759, 2683, 2702] 6 [0, 8143, 0, 1, 0, 0] 7 [1, 1615, 1648, 1, 1636, 1595, 1648] 8 [0, 1963, 0, 2074, 0, 2040, 0, 2067] 9 [0, 2682, 0, 1, 2692, 0, 0, 2769, 0] 10 [0, 0, 0, 2683, 0, 0, 0, 2759, 0, 2702] 11 [0, 904, 916, 922, 895, 896, 929, 1, 911, 880, 890] 12 [0, 4003, 0, 1, 0, 0, 0, 4140, 0, 0, 0, 0] Density information: A(x) at x=10,100,1000,...: [2, 9, 41, 203, 1216, 8144] A(x)/x at x=10,100,1000,...: 0.2,0.09,0.041,0.0203,0.01216,0.008144, First 100 first differences: [4, 6, 6, 18, 6, 24, 12, 18, 6, 6, 18, 36, 30, 30, 6, 48, 30, 6, 36, 30, 18, 42, 18, 6, 24, 12, 114, 30, 30, 66, 18, 12, 54, 30, 6, 18, 6, 24, 30, 30, 42, 78, 6, 120, 66, 18, 6, 120, 6, 18, 36, 6, 60, 18, 12, 18, 12, 54, 30, 90, 84, 6, 120, 6, 84, 54, 66, 36, 30, 24, 54, 30, 12, 48, 36, 66, 78, 42, 24, 6, 18, 42, 48, 36, 24, 96, 66, 18, 42, 84, 24, 30, 36, 66, 24, 114, 6, 66, 84, 60] First 99 second differences: [2,0,12,-12,18,-12,6,-12,0,12,18,-6,0,-24,42,-18,-24,30,-6,-12,24,-24,-12,18,-12, 102,-84,0,36,-48,-6,42,-24,-24,12,-12,18,6,0,12,36,-72,114,-54,-48,-12,114,-114, 12,18,-30,54,-42,-6,6,-6,42,-24,60,-6,-78,114,-114,78,-30,12,-30,-6,-6,30,-24, -18,36,-12,30,12,-36,-18,-18,12,24,6,-12,-12,72,-30,-48,24,42,-60,6,6,30,-42,90, -108,60,18,-24] Distinct line at 7350Hz corresponding to 44100/6. We can observe that this sequence will not contain any primes that are congruent to 5 mod 6 because for any primes of the form 6n-1 it will not hold true that 6n+3 is prime as it is divisible by 3. -- David Oh