OFFSET
1,2
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
Max Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems
G. A. Miller, On the subgroups of an abelian group, The Annals of Mathematics, 2nd Ser. 6:1 (1904), pp. 1-6.
L. Toth, The number of subgroups of the group Z_m x Z_n x Z_r x Z_s, arXiv:1611.03302 [math.GR], (2016).
PROG
(PARI) \\ For numsubgrp, see the Alekseyev link.
a(n)=my(f=factor(n)); prod(i=1, #f~, numsubgrp(f[i, 1], f[i, 2]*[1, 1, 1, 1])) \\ Charles R Greathouse IV, Dec 27 2016
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
Laszlo Toth, Dec 27 2016
EXTENSIONS
Terms a(32) and beyond from Charles R Greathouse IV, Dec 27 2016
STATUS
approved