A098215 Numbers n such that reverse(sigma(n)) = n - phi(n) = cototient(n).

136, 261, 295, 493, 1218, 1576, 15976, 159976, 715381, 717181, 746341, 987109, 1585576, 5989003, 13390567, 14400136, 19326607, 78753211, 144144136, 145454536, 158401576, 275675661, 713791681, 737098261, 1440000136, 1441584136, 1454414536, 1455998536

Offset

1,1

Links

Table of n, a(n) for n=1..28.

Example

n=5989003: sigma(n) = 5994000 and n - phi(n) = 4995

Mathematica

Do[ If[ FromDigits[ Reverse[ IntegerDigits[ DivisorSigma[1, n]]]] == n - EulerPhi[n], Print[n]], {n, 10^8}] (* Robert G. Wilson v, Oct 23 2004 *)

Crossrefs

Cf. A069225, A000203, A000010.

Sequence in context: A262615 A101335 A349092 * A247439 A183635 A116223

Adjacent sequences: A098212 A098213 A098214 * A098216 A098217 A098218

Keyword

base,nonn

Author

Labos Elemer, Oct 22 2004

Extensions

More terms from Robert G. Wilson v, Oct 27 2004

a(19)-a(28) from Donovan Johnson, Jan 14 2011

Status

approved