login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A098215 Numbers n such that reverse(sigma(n)) = n - phi(n) = cototient(n). 0
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 (list; graph; refs; listen; history; text; internal format)
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: A264958 A262615 A101335 * 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 9 08:37 EST 2021. Contains 349627 sequences. (Running on oeis4.)