OFFSET
1,1
MATHEMATICA
Select[ Range[ 10^6 ], DivisorSigma[ 1, EulerPhi[ # ] ] == EulerPhi[ DivisorSigma[ 1, # ] - # ] & ]
PROG
(Python)
from sympy import divisor_sigma as sigma, totient as phi
def aupto(limit):
for k in range(2, limit):
if sigma(phi(k)) == phi(sigma(k) - k): print(k, end=", ")
aupto(10**4) # Michael S. Branicky, Feb 18 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Dec 26 2000
EXTENSIONS
a(8)-a(29) from Donovan Johnson, Jan 19 2012
STATUS
approved