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A067797 Numbers k such that phi(k) + phi(k+1) = k+2. 1
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
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
Sequence in context: A090938 A058229 A087271 * A203633 A190630 A013285
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 07 2002
EXTENSIONS
More terms from Michel Marcus, Nov 23 2013
STATUS
approved

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Last modified July 18 06:54 EDT 2024. Contains 374377 sequences. (Running on oeis4.)