A349141 a(n) = Sum_{d|n} phi(n/d) * A348507(d), where A348507(n) = A003959(n) - n, and A003959 is fully multiplicative with a(p) = (p+1).

0, 1, 1, 6, 1, 9, 1, 26, 9, 13, 1, 44, 1, 17, 15, 98, 1, 57, 1, 68, 19, 25, 1, 176, 15, 29, 57, 92, 1, 105, 1, 342, 27, 37, 23, 252, 1, 41, 31, 280, 1, 141, 1, 140, 111, 49, 1, 636, 21, 125, 39, 164, 1, 309, 31, 384, 43, 61, 1, 480, 1, 65, 147, 1138, 35, 213, 1, 212, 51, 209, 1, 960, 1, 77, 155, 236, 35, 249, 1, 1028

Offset

1,4

Comments

Dirichlet convolution of Euler phi (A000010) with A348507.

Möbius transform of A349140.

Links

Antti Karttunen, Table of n, a(n) for n = 1..16384

Formula

a(n) = Sum_{d|n} A000010(n/d) * A348507(d).

a(n) = Sum_{d|n} A008683(n/d) * A349140(d).

a(n) = Sum_{k=1..n} A348507(gcd(n,k)).

For all n >= 1, a(n) >= A347131(n) >= A348981(n).

a(n) = A349171(n) - A018804(n). - Antti Karttunen, Nov 14 2021

Mathematica

f[p_, e_] := (p + 1)^e; s[1] = 1; s[n_] := Times @@ f @@@ FactorInteger[n]; a[n_] := DivisorSum[n, (s[#] - #) * EulerPhi[n/#] &]; Array[a, 100] (* Amiram Eldar, Nov 08 2021 *)

Prog

(PARI)
A003959(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1]++); factorback(f); };
A348507(n) = (A003959(n) - n);
A349141(n) = sumdiv(n, d, eulerphi(d)*A348507(n/d));

Crossrefs

Cf. A000010, A003959, A008683, A018804, A348507, A349140 (inverse Möbius transform), A349142, A349143, A349171.

Cf. also A347131, A348981.

Sequence in context: A202351 A111507 A117236 * A358968 A246771 A176397

Adjacent sequences: A349138 A349139 A349140 * A349142 A349143 A349144

Keyword

nonn

Author

Antti Karttunen, Nov 08 2021

Status

approved