OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
FORMULA
MAPLE
A280729 := proc(n)
local p;
p := ithprime(n+1) ;
(p-1)/2+numtheory[phi](p-1) ;
end proc: # R. J. Mathar, Jan 10 2017
MATHEMATICA
Table[(n - 1)/2 + EulerPhi[n - 1], {n, Prime[Range[2, 100]]}]
PROG
(Magma) [(NthPrime(n)-1)/2+EulerPhi(NthPrime(n)-1): n in [2..100]];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jan 10 2017
STATUS
approved