A305333 Let p be the n-th base-5 Wieferich prime (A123692). a(n) is the value of p-1 divided by the multiplicative order of 5 (mod p^2).

1, 2, 1, 4, 1, 1, 16

Offset: 1

Author

Felix Fröhlich, May 30 2018

Keywords

• nonn
• hard
• more

Crossrefs

Cf. A123692, A211241, A305331, A305332.

Programs

PARI

v=[2, 20771, 40487, 53471161, 1645333507, 6692367337, 188748146801]; for(k=1, #v, my(ord=znorder(Mod(5, v[k]^2))); print1((v[k]-1)/ord, ", "))

Formula

a(n) = (A123692(n)-1)/A305332(n).