
EXAMPLE

For a(1), the sequence is 1, 2, 3, 5, 11, 2, 3, 5, 11, 2, 3,
5, 11, ... The sequence has period {2, 3, 5, 11} so a(1) = 4.
For a(2) see the A112279: 1, 2, 3, 5, 11, 31, 127, 103, 5,
11, 31, 127, 103, 5, 11, ..., . This sequence has a cyclic length of 5.


MATHEMATICA

f[n_] := Block[{k = 1, a}, a[0] = 1; a[i_] := a[i] = Prime[Mod[a[i  1], 10^n]]; While[t = Table[a[i], {i, 0, k  1}]; MemberQ[t, a[k]] == False, k++ ]; k + 1  Flatten[ Position[ t, a[k]]][[1]]]; Array[ f, 10]
