Number of composite numbers around 3^n.
0, 3, 5, 3, 9, 5, 23, 9, 5, 21, 35, 73, 29, 9, 17, 123, 43, 19, 69, 15, 59, 5, 51, 29, 33, 21, 41, 47, 143, 29, 19, 103, 121, 89, 49, 11, 51, 17, 139, 155, 71, 125, 125, 41, 67, 89, 97, 99, 65, 73, 49, 173, 29, 37, 125, 71, 29, 377, 101, 175, 107, 129, 29, 195
1
T. D. Noe, Plot of 1000 terms
T. D. Noe, Table of 1000 terms
(Mma) Join[{0}, Table[NextPrime[3^n] - NextPrime[3^n, -1] - 1, {n, 2, 50}]]
nonn
T. D. Noe, Mar 09 2015