[seqfan] Re: What defines A133992

[Douglas McNeil]

> Can anyone figure out what the correct definition of
> http://oeis.org/classic/A133992
> currently defined as Sigma(prime(n)*prime(prime(n))-1) could be?

I think his Sigma = number of divisors.

sage: A133992
[2, 4, 8, 4, 12, 12, 8, 16, 18, 16]
sage: a = [number_of_divisors(nth_prime(n)*nth_prime(nth_prime(n))-1)
for n in range(1, 12)]
sage: a
[2, 4, 8, 4, 12, 12, 8, 16, 18, 16, 24]


Doug

-- 
Department of Earth Sciences
University of Hong Kong