OFFSET
1,1
REFERENCES
Jean-Marie De Koninck, Those Fascinating Numbers, American Mathematical Society, 2009, p. 34, entry 105 and p. 130, entry 1484.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
1484 is in the sequence since phi(1484) = 624, phi(1485) = 720, phi(1486) = 742, and phi(1487) = 1486, and 624 < 720 < 742 < 1486.
MATHEMATICA
aQ[n_] := AllTrue[Differences @ EulerPhi[n + Range[0, 3]], # > 0 &]; Select[Range[18000], aQ]
PROG
(PARI) ok(k)={for(i=0, 2, if(eulerphi(k+i) >= eulerphi(k+i+1), return(0))); 1}
{ select(ok, [1..20000]) } \\ Andrew Howroyd, Sep 28 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Sep 28 2019
STATUS
approved