A037170 Numbers n such that n = pi(n) + phi(n), where pi = A000720, phi = A000010.

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

Links

Table of n, a(n) for n=1..26.

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

Adjacent sequences: A037167 A037168 A037169 * A037171 A037172 A037173

Keyword

nonn

Author

Naohiro Nomoto

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