A282601 a(n) = Sum_(k=1..phi(n)/2) floor(d_k/2) where d_k are the totatives of n.

0, 0, 0, 0, 1, 0, 2, 1, 3, 1, 6, 2, 9, 3, 6, 6, 16, 5, 20, 8, 14, 10, 30, 10, 29, 15, 28, 18, 49, 14, 56, 28, 38, 28, 48, 24, 81, 36, 54, 36, 100, 30, 110, 50, 64, 55, 132, 44, 124, 57, 96, 72, 169, 56, 130, 78, 122, 91, 210, 56, 225, 105, 136, 120, 186, 80, 272, 128, 182, 102

Offset

1,7

Comments

The totatives of n are the numbers k <= n with gcd(k,n) = 1.

Links

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

David Zmiaikou, Origamis and permutation groups, Thesis, 2011. See p. 65.

Prog

(PARI) a(n) = {vn = vector(n, k, k); vt = select(x->(gcd(x, n) == 1), vn); sum(k=1, #vt\2, vt[k]\2); }

Crossrefs

Cf. A000010, A023896, A038566, A066840, A282600.

Sequence in context: A082588 A006241 A336105 * A363273 A034869 A205858

Adjacent sequences: A282598 A282599 A282600 * A282602 A282603 A282604

Keyword

nonn

Author

Michel Marcus, Feb 19 2017

Status

approved