|
|
A072589
|
|
n, phi(n) and sigma(n) end with the same digit.
|
|
1
|
|
|
1, 84, 204, 294, 364, 440, 444, 564, 600, 644, 804, 884, 950, 1000, 1134, 1164, 1204, 1240, 1274, 1284, 1320, 1344, 1350, 1400, 1450, 1484, 1524, 1564, 1640, 1644, 1734, 1884, 1900, 1924, 2004, 2044, 2090, 2200, 2254, 2324, 2364, 2440, 2444, 2600, 2700, 2724
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
FORMULA
|
It seems that lim n -> infinity a(n)/n exists around 40.
|
|
MATHEMATICA
|
Select[Range[3000], Last[IntegerDigits[#]]==Last[ IntegerDigits[ EulerPhi[ #]]] == Last[ IntegerDigits[ DivisorSigma[1, #]]]&] (* Harvey P. Dale, Aug 03 2014 *)
|
|
PROG
|
(PARI) isok(n) = ((n % 10) == (eulerphi(n) % 10)) && ((n % 10) == (sigma(n) % 10)); \\ Michel Marcus, Nov 26 2013
|
|
CROSSREFS
|
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|