A262086 Numbers k such that phi(k + 10) = phi(k) + 10, where phi(k) = A000010(k) is Euler's totient function.

3, 7, 13, 19, 31, 36, 37, 43, 61, 73, 79, 97, 103, 127, 139, 157, 163, 181, 223, 229, 241, 271, 283, 307, 337, 349, 373, 379, 409, 421, 433, 439, 457, 499, 547, 577, 607, 631, 643, 673, 691, 709, 733, 751, 787, 811, 829, 853, 877, 919, 937, 967

Offset

1,1

Comments

The only composite term less than 10^11 is 36. - Giovanni Resta, Sep 14 2015

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Seiichi Manyama)

Wikipedia, Euler's totient function.

Example

3 is in the sequence since phi(13) = phi(3) + 10.

Mathematica

Select[Range@1000, EulerPhi@(# + 10) == EulerPhi[#] + 10 &] (* Vincenzo Librandi, Sep 11 2015 *)

Prog

(Magma) [n: n in [1..1000] | EulerPhi(n+10) eq EulerPhi(n)+10]; // Vincenzo Librandi, Sep 11 2015
(PARI) is(n)=eulerphi(n + 10) == eulerphi(n) + 10 \\ Anders Hellström, Sep 11 2015

Crossrefs

Cf. A000010, A023203.

Cf. A001838 (k=2), A056772 (k=4), A262084 (k=6), A262085 (k=8), this sequence (k=10).

Sequence in context: A031215 A099957 A086148 * A205956 A215907 A007645

Adjacent sequences: A262083 A262084 A262085 * A262087 A262088 A262089

Keyword

nonn,easy

Author

Kevin J. Gomez, Sep 10 2015

Status

approved