A072393 -id:A072393 - cp's OEIS frontend

A114926 Numbers n such that pi(n)=reversal(n)-n.

1, 23, 526, 536, 1802, 4735, 17191, 38524, 235652, 36235483, 1086331411, 5316125655, 7202194357, 49294058315, 327040088933

Offset: 1

Farideh Firoozbakht, Feb 03 2006

a(16) > 10^13. - Giovanni Resta, Aug 08 2019

			36235483 is in the sequence because pi(36235483)=2217780= 38453263-36235483=reversal(36235483)-36235483.

Cf. A072393, A100415.

Do[If[PrimePi[n]==FromDigits[Reverse[IntegerDigits[n]]] -n,Print[n]],{n,30000000}]

a(11)-a(15) from Giovanni Resta, Aug 08 2019

A115926 Numbers k such that phi(k) = reversal(k)-k.

Original entry on oeis.org

37, 397, 1853, 15503, 48776, 198683, 200882, 1061361, 3542805, 3564217, 3868867, 3962197, 4438616, 19844683, 198444683, 202195682, 309520655, 431092646, 439419646, 500729929, 535973599, 3566790217, 3963436297, 4149753226, 17296101143, 39560402197

Offset: 1

Farideh Firoozbakht, Jan 31 2006

All primes of the form 4*10^n-3 are in the sequence because if 4*10^n-3 is prime then phi(4*10^n-3)=(4*10^n-4) =(8*10^n-7)-(4*10^n-3)=reversal(4*10^n-3)-(4*10^n-3).
Also if n>1 and p=(94*10^n+113)/9 is prime then 19*p is in the sequence (the proof is easy). Next term is greater than 125*10^6.
If p=(1/303)*(232*10^(4n)+71) is prime then 7*p is in the sequence (the proof is easy). The first four such terms happen for n=2, 101, 104 & 444 and numbers of digits of these terms of the sequence are 9, 405, 417 & 1777 respectively. - Farideh Firoozbakht, Jan 02 2008
a(32) > 10^12. - Giovanni Resta, Oct 28 2012

			If n=37, phi(37) = 36 = 73-37.

Giovanni Resta, Table of n, a(n) for n = 1..31

Cf. A072393.

Do[If[EulerPhi[n]==FromDigits[Reverse[IntegerDigits[n]]]-n, Print[n]], {n, 600000000}] (* Jessica M. Cornwall (jmc510(AT)psu.edu), Apr 05 2006 *)

More terms from Jessica M. Cornwall (jmc510(AT)psu.edu), Apr 05 2006

a(22)-a(31) from Giovanni Resta, Oct 28 2012

cp's OEIS Frontend

A114926 Numbers n such that pi(n)=reversal(n)-n.

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