OFFSET
1,3
COMMENTS
a(n) > 0 for {19, 23, 29, 31, 37, 43, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97}. Does this hold only for special primes?
No: composites for which a(n) > 0 include 121, 289, 437, 529, 667, 671, 697, 703, 713, 731, .... - Robert Israel, Jan 23 2021
LINKS
Robert Israel, Table of n, a(n) for n = 1..3322
MATHEMATICA
g[x_] := EulerPhi[x] Table[Apply[Plus, Table[Binomial[g[n], g[j]], {j, 0, n}]], {n, 1, 50}]
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Labos Elemer, Jul 26 2002
STATUS
approved