A280729 (p-1)/2 + phi(p-1) as p runs through the odd primes.

2, 4, 5, 9, 10, 16, 15, 21, 26, 23, 30, 36, 33, 45, 50, 57, 46, 53, 59, 60, 63, 81, 84, 80, 90, 83, 105, 90, 104, 99, 113, 132, 113, 146, 115, 126, 135, 165, 170, 177, 138, 167, 160, 182, 159, 153, 183, 225, 186, 228, 215, 184, 225, 256, 261, 266, 207, 226, 236, 233

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Formula

a(n) = A098006(n)+2*A008330(n). - R. J. Mathar, Jan 10 2017

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

Cf. A098006.

Sequence in context: A071349 A282737 A039891 * A363283 A213011 A175265

Adjacent sequences: A280726 A280727 A280728 * A280730 A280731 A280732

Keyword

nonn,easy

Author

Vincenzo Librandi, Jan 10 2017

Status

approved