Number of composite numbers around 7^n.
0, 5, 9, 11, 23, 15, 5, 17, 9, 25, 53, 17, 75, 35, 67, 29, 59, 97, 115, 33, 57, 133, 89, 105, 65, 59, 35, 77, 195, 131, 19, 161, 45, 35, 95, 17, 331, 137, 109, 255, 105, 155, 125, 259, 177, 259, 143, 95, 29, 389, 159, 259, 147, 129, 113, 195, 123, 401, 327, 197
1
T. D. Noe, Plot of 1000 terms
T. D. Noe, Table of 1000 terms
(Mma) Join[{0}, Table[NextPrime[7^n] - NextPrime[7^n, -1] - 1, {n, 2, 50}]]
nonn
T. D. Noe, Mar 09 2015