OFFSET
1,2
COMMENTS
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MAPLE
isA306146 := proc(n)
local a239 ;
a239 := A023900(n) ;
if a239 >= 1 then
simplify( numtheory[phi](a239) = A023900(numtheory[phi](n)) );
else
false;
end if;
end proc:
for n from 1 to 1000 do
if isA306146(n) then
printf("%d, ", n) ;
end if;
end do: # R. J. Mathar, Feb 14 2019
MATHEMATICA
f[p_, e_] := 1 - p; d[1] = 1; d[n_] := Times @@ (f @@@ FactorInteger[n]); Select[Range[1324], (d1 = d[#]) > 0 && d[EulerPhi[#]] == EulerPhi[d1] &] (* Amiram Eldar, Feb 19 2020 *)
PROG
(PARI) a023900(n) = sumdivmult(n, d, d*moebius(d))
is(n) = sdm = a023900(n); if(sdm < 0, return(0), sdmphi = a023900(eulerphi(n)); eulerphi(sdm) == sdmphi) \\ David A. Corneth, Aug 17 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Torlach Rush, Aug 11 2018
STATUS
approved