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A056775 Numbers k such that phi(k+12) = phi(k) + 12. 1
5, 7, 11, 17, 19, 29, 31, 41, 45, 47, 59, 61, 65, 67, 71, 80, 89, 97, 99, 101, 112, 117, 127, 135, 137, 139, 151, 167, 171, 176, 179, 181, 196, 199, 207, 209, 211, 227, 229, 239, 251, 257, 269, 271, 272, 279, 281, 294, 304, 310, 312, 337, 347, 367, 369, 389 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Prime solutions are in A046133, common with primes in A015917.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harvey P. Dale)

EXAMPLE

65 is a term since phi(65) = 48, phi(65+12) = phi(77) = 60 = 48 + 12.

MATHEMATICA

Select[Range[400], EulerPhi[#]+12==EulerPhi[#+12]&] (* Harvey P. Dale, Jan 21 2013 *)

CROSSREFS

Cf. A000010, A001838, A015917, A054902, A046133, A046133.

Sequence in context: A200569 A110016 A254672 * A015917 A046133 A086136

Adjacent sequences:  A056772 A056773 A056774 * A056776 A056777 A056778

KEYWORD

nonn

AUTHOR

Labos Elemer, Aug 17 2000

STATUS

approved

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Last modified January 15 13:34 EST 2021. Contains 340187 sequences. (Running on oeis4.)