OFFSET
1,2
LINKS
Robert Israel, Table of n, a(n) for n = 1..1930
EXAMPLE
MAPLE
A6190:= proc(n) option remember; 3*procname(n-1)+procname(n-2) end proc:
A6190(0):= 0: A6190(1):= 1:
f:= proc(n) local k, i, g;
k:= A6190(n);
for i from 1 to n-1 do
g:= igcd(k, A6190(i));
while g > 1 do
k:= k/g;
g:= igcd(k, A6190(i));
od;
od;
k
end proc:
map(f, [$1..40]); # Robert Israel, Aug 02 2024
PROG
(PARI) T(n) = ([3, 1; 1, 0]^n)[2, 1]
b(n) = my(v=divisors(n)); prod(i=1, #v, T(v[i])^moebius(n/v[i]))
a(n) = if(isprime(n)&&!(13%n), 1543321, if(n!=6, b(n)/gcd(n, b(n)), 1))
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Jianing Song, Aug 06 2019
STATUS
approved