OFFSET
1,2
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
FORMULA
a(p) = 2p for p = primes (A000040).
From Robert Israel, Mar 24 2019: (Start)
a(p^k) = (k+1)! * p^(k*(k+1)/2) for primes p.
a(p*q) = 16*p^2*q^2 if p and q are distinct primes. (End)
EXAMPLE
a(6) = 1*tau(1) * 2*tau(2) * 3*tau(3) * 6*tau(6) = (1*1) * (2*2) * (3*2) * (6*4) = 576.
MAPLE
f:= proc(n) uses numtheory; local d;
mul(d*tau(d), d = divisors(n))
end proc:
map(f, [$1..100]); # Robert Israel, Mar 24 2019
MATHEMATICA
Table[n^(DivisorSigma[0, n]/2) * Product[DivisorSigma[0, k], {k, Divisors[n]}], {n, 1, 60}] (* Vaclav Kotesovec, Mar 10 2019 *)
PROG
(Magma) [&*[d * NumberOfDivisors(d): d in Divisors(n)]: n in [1..100]]
(PARI) a(n) = my(res = 1); fordiv(n, d, res *= d*numdiv(d)); res; \\ Michel Marcus, Mar 06 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Mar 05 2019
STATUS
approved