OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
FORMULA
EXAMPLE
MATHEMATICA
pf[x_] := Part[Reverse[Flatten[FactorInteger[x]]], 2] f[x_] := EulerPhi[pf[x]]-pf[EulerPhi[x]] Table[Prime[w]-f[Prime[w]], {w, 2, 128}]
PROG
(PARI) a(n)=if(n>1, my(f=factor(prime(n)-1)[, 1]); f[#f]+1, 2)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, May 10 2002
STATUS
approved