2306881201domain: NAppears in sequencesa(n) = A047848(4, n).at n=12A047852a(n) = (1/6) * (7^(n+1) - 3*(-1)^n + 2).at n=11A102303Primes of the form Sum[7^i, {i, 0, n}] + 1 - Mod[Sum[7^i, {i, 0, n}], 2].at n=3A102324