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A333992
a(n) is the multiplicative order of the n-th prime number q modulo (q-1)#.
0
1, 1, 2, 4, 6, 20, 60, 120, 144, 7920, 18480, 18480, 7920, 27720, 2520, 637560, 8288280, 480720240, 240360120, 480720240, 480720240, 480720240, 240360120, 9854764920, 19709529840, 9854764920, 16424608200, 670124014560, 88791431929200, 88791431929200
OFFSET
1,3
EXAMPLE
For n = 2, q = prime(2) = 3, we have (q-1)#=2, then the multiplicative order of q modulo (q-1)# is 1.
MAPLE
with(NumberTheory):
primorial := proc(n::integer)
local total := 1:
local count := 2;
for count from 2 to n do
if isprime(count) then
total *= count
endif;
end:
return total;
end proc:
numberOfTerms := 3;
List := [seq(MultiplicativeOrder(ithprime(i), primorial(ithprime[i]-1)), i=1..numberOfTerms)]
MATHEMATICA
a[n_] := MultiplicativeOrder[Prime[n], Times @@ Prime[Range[n-1]]];
a /@ Range[30] (* Jean-François Alcover, Nov 03 2020 *)
PROG
(PARI) a(n)={znorder(Mod(prime(n), vecprod(primes(n-1))))} \\ Andrew Howroyd, Sep 05 2020
CROSSREFS
Cf. A002110.
Sequence in context: A245766 A193774 A241210 * A176652 A251724 A326363
KEYWORD
nonn
AUTHOR
Yassine Lagrida, Sep 04 2020
EXTENSIONS
Terms a(16) and beyond from Andrew Howroyd, Sep 05 2020
STATUS
approved