OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
1 is a term since both 1 and 2 are phi-practical numbers.
MATHEMATICA
phiPracticalQ[n_] := If[n<1, False, If[n==1, True, (lst = Sort @ EulerPhi @ Divisors[n]; ok=True; Do[If[lst[[m]]>Sum[lst[[l]], {l, 1, m-1}]+1, (ok=False; Break[])], {m, 1, Length[lst]}]; ok)]]; Select[Range[40000], phiPracticalQ[#] && phiPracticalQ[#+1] &] (* after Frank M Jackson at A260653 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Apr 29 2020
STATUS
approved