A181835 The sum of the primes <= n that are strongly prime to n.

0, 0, 0, 0, 0, 3, 0, 5, 8, 12, 7, 10, 12, 23, 19, 24, 31, 39, 36, 53, 51, 60, 54, 64, 72, 90, 80, 82, 88, 91, 90, 119, 127, 144, 127, 129, 143, 155, 139, 160, 174, 190, 185, 226, 225, 260, 248, 256

Offset

0,6

Comments

k is strongly prime to n iff k is relatively prime to n and k does not divide n-1.

Links

Table of n, a(n) for n=0..47.

Peter Luschny, Strong coprimality.

Example

a(11) = 3 + 7 = 10.

Maple

with(numtheory):
Primes := n -> select(k->isprime(k), {$1..n}):
StrongCoprimes := n -> select(k->igcd(k, n)=1, {$1..n}) minus divisors(n-1):
StrongCoprimePrimes := n -> Primes(n) intersect StrongCoprimes(n):
A181835 := proc(n) local i; add(i, i=StrongCoprimePrimes(n)) end:

Mathematica

a[n_] := Select[Range[2, n], PrimeQ[#] && CoprimeQ[#, n] && !Divisible[n-1, #] &] // Total; Table[a[n], {n, 0, 47}] (* Jean-François Alcover, Jun 28 2013 *)

Crossrefs

Cf. A181830, A181831, A181832, A181834, A181836, A066911.

Sequence in context: A013673 A188639 A103229 * A076296 A260934 A143280

Adjacent sequences: A181832 A181833 A181834 * A181836 A181837 A181838

Keyword

nonn

Author

Peter Luschny, Nov 17 2010

Status

approved