1,1

Except for twin primes, there are 2n numbers congruent to {2, 4} mod 6 between two consecutive primes

a(n) = 2 iff there are twin primes between two numbers congruent to {2, 4} mod 6.

Table of n, a(n) for n=1..87.

Sequence in context: A142242 A050314 A316344 * A080378 A243865 A120439

Adjacent sequences: A122154 A122155 A122156 * A122158 A122159 A122160

easy,nonn

Giovanni Teofilatto, Oct 29 2006, corrected Nov 01 2006

approved