login
The OEIS is supported by the many generous donors to the OEIS 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 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A279184 Numbers k such that phi(6k) = phi(6k+2), where phi is Euler's totient function A000010. 3
268, 723, 9718, 9858, 13498, 15738, 35898, 60363, 75168, 75973, 87208, 88888, 98198, 126848, 135368, 141093, 161268, 221223, 233788, 301513, 328358, 330633, 419148, 507648, 527928, 543468, 551238, 556418, 586018, 725958, 772508, 964588, 985728 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..33.

Dov Jarden, Recurring Sequences, Riveon Lematematika, Jerusalem, 1966. [Annotated scanned copy] See p. 67.

MAPLE

select( k -> numtheory:-phi(6*k)=numtheory:-phi(6*k+2), [$1..10^6]); # Robert Israel, Dec 11 2016

MATHEMATICA

a = {}; Do[If[EulerPhi[6 k] == EulerPhi[6 k + 2], AppendTo[a, k]], {k, 1000000}]; a (* Vincenzo Librandi, Dec 11 2016 *)

PROG

(Magma) [n: n in [1..2*10^6] | EulerPhi(6*n) eq EulerPhi(6*n+2)]; // Vincenzo Librandi, Dec 11 2016

(PARI) isok(k) = eulerphi(6*k) == eulerphi(6*k+2); \\ Michel Marcus, Dec 11 2016

CROSSREFS

A279011 is the union of A279183 and A279184. Cf. A000010.

Sequence in context: A304388 A234878 A194774 * A237228 A190352 A235175

Adjacent sequences: A279181 A279182 A279183 * A279185 A279186 A279187

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 10 2016

EXTENSIONS

a(8)-a(33) from Robert Israel, Dec 11 2016

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 7 01:51 EST 2022. Contains 358649 sequences. (Running on oeis4.)