OFFSET
1,2
LINKS
M. Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems: invphi.gp, Oct. 2005
EXAMPLE
The possible values of sigma(x) are A002191 = {1, 3, 4, 6, 7, 8, 12, ...}.
The 7th value is 12 = sigma(x) for x = 6 or 11. Since 11 is the largest such value, a(7) = 11.
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Nov 22 2019
STATUS
approved