OFFSET
3,1
COMMENTS
Fermat quotients in base 3/2.
For n > 3, a(n) is divisible by 5.
Primes p such that p^2 divides 3^(p-1) - 2^(p-1) (base-3/2 Wieferich primes) are p = 23, ... What's the next?
LINKS
G. C. Greubel, Table of n, a(n) for n = 3..317
EXAMPLE
For n = 3, prime(3) = 5 and a(3) = (3^4 - 2^4)/5 = 13.
For n = 4, prime(4) = 7 and a(4) = (3^6 - 2^6)/7 = 95.
MATHEMATICA
p[n_]:=Prime[n]; a[n_]:=(3^(p[n]-1) - 2^(p[n]-1))/p[n]; Array[a, 50, 3] (* Stefano Spezia, Oct 11 2018 *)
PROG
(PARI) a(n) = my(p=prime(n)); (3^(p-1) - 2^(p-1))/p
(Magma) [(3^(p-1) - 2^(p-1)) div p: p in PrimesInInterval(4, 100)]; // Vincenzo Librandi, Oct 12 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Jianing Song, Oct 09 2018
STATUS
approved