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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
OFFSET
1,2
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
Intersection of A072566 and A072585.
Sequence in context: A306514 A044416 A044797 * A181113 A254464 A135804
KEYWORD
base,nonn
AUTHOR
Benoit Cloitre, Aug 06 2002
STATUS
approved