OFFSET
1,2
COMMENTS
After the first term a(1) = 1, the next odd term is a(25) = 3465, the next term that is coprime to 6 is a(308) = 95095, and the next term that is coprime to 30 is a(13544) = 10023013.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
60 is a term since A378056(60) = 4620 = 60 * 77 is divisible by 60.
MATHEMATICA
s[n_] := Module[{d = Divisors[n]}, GCD[LCM @@ (d + 1), LCM @@ (Rest @ d - 1)]]; s[1] = 1; Select[Range[10000], Divisible[s[#], #] &]
PROG
(PARI) is(k) = {my(d = divisors(k)); !(lcm(apply(x->x+1, d)) % k) && !(lcm(apply(x -> if(x > 1, x-1, x), d)) % k); }
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Nov 15 2024
STATUS
approved