OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Paul Loomis and Florian Luca, On totient abundant numbers, Electronic Journal of Combinatorial Number Theory, Vol. 8, #A06 (2008).
EXAMPLE
19 is a totient abundant number since A092693(19) = phi(19) + phi(phi(19)) + ... = 18 + 6 + 2 + 1 = 27 > 19.
MATHEMATICA
totAbundantQ[n_] := Plus @@ FixedPointList[ EulerPhi@ # &, n] > 2*n+1; Select[Range[1000], totAbundantQ]
PROG
(Python)
from sympy import totient
def a092693(n): return 0 if n==1 else totient(n) + a092693(totient(n))
print([n for n in range(1, 201) if a092693(n) > n]) # Indranil Ghosh, May 05 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, May 05 2017
STATUS
approved