OFFSET
1,1
COMMENTS
Is there an upper bound for a(n) for a given n? - Michael B. Porter, Apr 06 2013
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..1000
EXAMPLE
a(3) = 27 since phi(27 - 3) = phi(24) = 8 and phi(27 + 3) = phi(30) = 8, and 27 is the smallest number greater than 3 for which the two are equal.
PROG
(PARI) /* will not terminate if k does not exist */
a218446(n) = {local(k); k = n + 1; while(eulerphi(k - n) <> eulerphi(k + n), k = k + 1); k} \\ Michael B. Porter, Mar 30 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Irina Gerasimova, Mar 26 2013
EXTENSIONS
Extended by R. J. Mathar, Mar 27 2013
STATUS
approved