OFFSET
1,1
COMMENTS
a(15) <= 1625589504000. a(16) <= 26009432064000. a(17) <= 442160345088000. [Donovan Johnson, Feb 05 2010]
EXAMPLE
Solutions to x-Phi[x]=720 are {1008,1424,1432,1436,1438} of which the smallest is a(6)=1008.
PROG
(PARI) a(n) = my(x=1); while(x-eulerphi(x) != n!, x++); x; \\ Michel Marcus, Aug 24 2019
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Labos Elemer, Dec 10 2001
EXTENSIONS
a(12)-a(14) from Donovan Johnson, Feb 05 2010
STATUS
approved