A346482 - OEIS

A346482

Dirichlet inverse of A005171, the characteristic function of nonprimes.

1, 0, 0, -1, 0, -1, 0, -1, -1, -1, 0, -1, 0, -1, -1, 0, 0, -1, 0, -1, -1, -1, 0, 1, -1, -1, -1, -1, 0, -1, 0, 1, -1, -1, -1, 2, 0, -1, -1, 1, 0, -1, 0, -1, -1, -1, 0, 3, -1, -1, -1, -1, 0, 1, -1, 1, -1, -1, 0, 3, 0, -1, -1, 1, -1, -1, 0, -1, -1, -1, 0, 5, 0, -1, -1, -1, -1, -1, 0, 3, 0, -1, 0, 3, -1, -1, -1, 1, 0, 3

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OFFSET

1,36

COMMENTS

In addition to A168645, -1's occur also in the following positions: 256, 512, 6561, 16384, 19683, 32768, 390625, 1048576, ...

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..20000

FORMULA

a(1) = 1; and for n > 2, a(n) = -Sum_{d|n, d<n} a(d) * A005171(n/d).

a(n) = A346483(n) - A005171(n).

PROG

(PARI)

up_to = 65537;

DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(d<n, v[n/d]*u[d], 0)))); (u) }; \\ Compute the Dirichlet inverse of the sequence given in input vector v.

A005171(n) = (1-isprime(n));

v346482 = DirInverseCorrect(vector(up_to, n, A005171(n)));

A346482(n) = v346482[n];

CROSSREFS

Cf. A005171, A010051, A018252, A168645, A346483.

Union of A000040 and A346484 gives the positions of zeros.

Sequence in context: A363877 A322452 A076754 * A364043 A339933 A101659

Adjacent sequences: A346479 A346480 A346481 * A346483 A346484 A346485

KEYWORD

sign

AUTHOR

Mats Granvik and Antti Karttunen, Aug 17 2021

STATUS

approved