Voozh

A067797

Numbers k such that phi(k) + phi(k+1) = k+2.

4, 6, 8, 50, 74, 110, 170, 174, 890, 902, 1310, 1434, 1826, 2714, 4190, 5030, 6494, 8234, 8474, 10142, 14390, 31670, 32394, 40514, 89990, 95174, 101834, 102554, 135374, 151754, 173942, 206054, 248394, 259694, 288266, 330614, 516242, 650654, 780554, 913994, 941714

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..72

MATHEMATICA

Select[Range[10^6], EulerPhi[#]+EulerPhi[#+1]==#+2&] (* Harvey P. Dale, Apr 04 2019 *)

PROG

(PARI) isok(n) = eulerphi(n) + eulerphi(n+1) == n+2; \\ Michel Marcus, Nov 23 2013

CROSSREFS

Cf. A000010, A092404.

Sequence in context: A090938 A058229 A087271 * A203633 A190630 A390123