OFFSET
2,2
COMMENTS
a(n) = 128 if prime(n-1) and prime(n) are twin primes and prime(n-1)>128. - Robert Israel, Feb 12 2020
LINKS
Robert Israel, Table of n, a(n) for n = 2..10000
EXAMPLE
a(1)=1 because 3^7 = 1 mod 2
a(2)=2 because 5^7 = 2 mod 3
MAPLE
seq(ithprime(n)&^7 mod ithprime(n-1), n=2..100); # Robert Israel, Feb 12 2020
MATHEMATICA
Table[Mod[Prime[n]^7, Prime[n - 1]], {n, 2, 50}]
(* The following program is more efficient because it only generates each prime once, but it is less easy to understand: *)
PowerMod[Last[#], 7, First[#]]&/@Partition[Prime[Range[60]], 2, 1] (* Harvey P. Dale, Sep 02 2016 *)
PROG
(Magma) [NthPrime(n)^7 mod NthPrime(n-1): n in [2..50]]; // Bruno Berselli, May 23 2011
(PARI) a(n) = my(p=prime(n)); lift(Mod(p, precprime(p-1))); \\ Michel Marcus, Mar 17 2023
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Artur Jasinski, Mar 26 2008
STATUS
approved