A342436 a(n) = Sum_{k=1..n} gcd(k,n)^(gcd(k,n) - 1).

1, 3, 11, 68, 629, 7791, 117655, 2097224, 43046745, 1000000637, 25937424611, 743008378618, 23298085122493, 793714773371811, 29192926025391919, 1152921504608944272, 48661191875666868497, 2185911559738739594277, 104127350297911241532859

Offset

1,2

Links

Seiichi Manyama, Table of n, a(n) for n = 1..387

Formula

a(n) = Sum_{d|n} phi(n/d) * d^(d-1).

Mathematica

a[n_] := Sum[GCD[k, n]^(GCD[k, n] - 1), {k, 1, n}]; Array[a, 20] (* Amiram Eldar, Mar 12 2021 *)

Prog

(PARI) a(n) = sum(k=1, n, gcd(k, n)^(gcd(k, n)-1));
(PARI) a(n) = sumdiv(n, d, eulerphi(n/d)*d^(d-1));

Crossrefs

Cf. A000010, A056665, A342421, A342423, A342435.

Sequence in context: A201259 A177008 A218923 * A342394 A342370 A345094

Adjacent sequences: A342433 A342434 A342435 * A342437 A342438 A342439

Keyword

nonn

Author

Seiichi Manyama, Mar 12 2021

Status

approved