OFFSET
1,4
COMMENTS
a(n) is the product of the terms in row n of A136178.
LINKS
Diana Mecum, Table of n, a(n) for n = 1..796
EXAMPLE
The positive divisors of 20 are 1,2,4,5,10,20; gcd(1,2)=1, gcd(2,4)=2, gcd(4,5)=1, gcd(5,10)=5, and gcd(10,20)=10, so a(20) = 1*2*1*5*10 = 100.
MATHEMATICA
Table[Times @@ Map[GCD @@ # &, Partition[Divisors@ n, 2, 1]], {n, 69}] (* Michael De Vlieger, Sep 21 2017 *)
PROG
(PARI) a(n) = my(vd = divisors(n)); prod(k=1, #vd-1, gcd(vd[k], vd[k+1])); \\ Michel Marcus, Sep 22 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Dec 19 2007
EXTENSIONS
a(26) and beyond from Diana L. Mecum, Dec 29 2008
STATUS
approved