OFFSET
1,2
COMMENTS
LINKS
Ray Chandler, Table of n, a(n) for n = 1..10000
FORMULA
Apparently, a(n) = A331294(n + 3) if n > 5. - Lorenzo Sauras Altuzarra, Sep 18 2022
EXAMPLE
9 is a term because Sum_{d|9} tau(d) = 1+2+3 = Product_{d|9} tau(d) = 1*2*3 = 6.
MATHEMATICA
Select[Range@ 37500, Total@ # == Times @@ # &@ Map[DivisorSigma[0, #] &, Divisors@ #] &] (* Michael De Vlieger, Dec 25 2016 *)
PROG
(Magma) [n: n in [1..1000000] | &*[NumberOfDivisors(d): d in Divisors(n)] eq &+[NumberOfDivisors(d): d in Divisors(n)]]
(PARI) isok(n) = my(d = divisors(n), nd = apply(numdiv, d)); vecsum(nd) == prod(k=1, #nd, nd[k]); \\ Michel Marcus, Jun 26 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Dec 25 2016
STATUS
approved