A128861 Let p = n-th odd prime; a(n) = number of primitive roots of p which might be expected to be relatively prime to p-1, that is, a(n) = phi(p-1)^2/(p-1) rounded to the nearest integer.

1, 1, 1, 2, 1, 4, 2, 5, 5, 2, 4, 6, 3, 11, 11, 14, 4, 6, 8, 8, 7, 20, 18, 11, 16, 10, 26, 12, 21, 10, 18, 30, 14, 35, 11, 15, 18, 41, 41, 44, 13, 27, 21, 36, 18, 11, 23, 56, 23, 54, 39, 17, 40, 64, 65, 65, 19, 28, 33, 30, 71, 30, 46, 30, 77, 19, 27, 86, 36, 73

Offset

1,4

References

R. Osborn, Tables of All Primitive Roots of Odd Primes Less Than 1000, Univ. Texas Press, Austin, TX, 1961, pp. 69-70.

Links

Table of n, a(n) for n=1..70.

Maple

A128861 := proc(n) local p ; p := ithprime(n+1) ; round( (numtheory[phi](p-1))^2 / (p-1) ) ; end: seq(A128861(n), n=1..70) ; # R. J. Mathar, Oct 31 2007

Crossrefs

Sequence in context: A008742 A029136 A001479 * A161307 A161241 A161026

Adjacent sequences: A128858 A128859 A128860 * A128862 A128863 A128864

Keyword

nonn,easy

Author

N. J. A. Sloane, Apr 20 2007

Extensions

More terms from R. J. Mathar, Oct 31 2007

Status

approved