OFFSET
1,2
LINKS
Ivan Neretin, Table of n, a(n) for n = 1..10000
EXAMPLE
MATHEMATICA
tpQ[n_]:=Module[{c=6EulerPhi[n]}, PrimeQ[c-1]&&PrimeQ[c+1]]; Select[ Range[ 300], tpQ] (* Harvey P. Dale, May 11 2011 *)
Select[Range[250], AllTrue[6*EulerPhi[#]+{1, -1}, PrimeQ]&] (* Harvey P. Dale, Oct 12 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Feb 10 2003
STATUS
approved