OFFSET
1,2
EXAMPLE
For n = 4; sigma(4) = 7; a(n) = 1*2*3*4*5*6*7 = 5040.
MATHEMATICA
DivisorSigma[1, Range[20]]! (* Harvey P. Dale, Apr 09 2019 *)
PROG
(PARI) a(n)=sigma(n)! \\ Charles R Greathouse IV, Feb 13 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jan 12 2011
EXTENSIONS
Corrected and extended by Harvey P. Dale, Apr 09 2019
STATUS
approved