OFFSET
1,1
COMMENTS
Includes 6*A023204. Thus Dickson's conjecture implies the sequence is infinite. - Robert Israel, Jan 10 2019
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..3000
MAPLE
filter:= n -> (numtheory:-sigma(n)/numtheory:-phi(n+9))::integer:
select(filter, [$1..1000]); # Robert Israel, Jan 10 2019
MATHEMATICA
Select[Range[1000], Divisible[DivisorSigma[1, #], EulerPhi[9 + #]] &] (* David Nacin, Mar 01 2012 *)
PROG
(PARI) is(n)=sigma(n)%(eulerphi(n)+9)==0 \\ Charles R Greathouse IV, Sep 25 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved