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A037170
Numbers n such that n = pi(n) + phi(n), where pi = A000720, phi = A000010.
4
1, 2, 4, 8, 27, 35, 215, 235, 2611, 65113, 174647, 1301317, 1302509, 5021647, 10885081, 36319939, 70112131, 70113559, 325575773, 514258883, 742327529, 1069238453, 18721771909, 27788563039, 113350570453, 835005036247
OFFSET
1,2
COMMENTS
a(25) > 10^11. - Donovan Johnson, Feb 06 2010
a(27) > 2.3*10^12. - Giovanni Resta, Mar 28 2017
EXAMPLE
From K. D. Bajpai, Jun 13 2017: (Start)
27 is in the sequence: pi(27) + phi(27) = 9 + 18 = 27.
35 is in the sequence: pi(35) + phi(35) = 11 + 24 = 35.
(End)
MAPLE
with(numtheory): select(n->pi(n)+phi(n)=n, [seq(n, n=1..100000)]); # K. D. Bajpai, Jun 13 2017
MATHEMATICA
Select[Range[10^5], # == PrimePi[#] + EulerPhi[#] &] (* Giovanni Resta, Mar 28 2017 *)
PROG
(PARI) is(n)=n==eulerphi(n)+primepi(n) \\ Charles R Greathouse IV, Feb 21 2013
(Magma) [n:n in[1..10000]|n eq k where k is EulerPhi(n)+#PrimesUpTo(n)]; // K. D. Bajpai, Jun 13 2017
CROSSREFS
Cf. A100411.
Sequence in context: A323948 A196265 A112285 * A212409 A006399 A326293
KEYWORD
nonn
EXTENSIONS
More terms from Alexander D. Healy, Mar 17 2001
a(20)-a(21) from Farideh Firoozbakht, Jul 20 2009
a(22)-a(24) from Donovan Johnson, Feb 06 2010
a(25)-a(26) from Giovanni Resta, Mar 28 2017
STATUS
approved