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A271102 a(n) is multiplicative with a(p^e) = -1 if e=2, a(p^e) = 0 if e=1 or e>2. 2
1, 0, 0, -1, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

Index entries for sequences computed from exponents in factorization of n

FORMULA

Dirichlet g.f.: 1 / zeta(2*s).

abs(a(n)) = A227291(n).

EXAMPLE

G.f. = x - x^4 - x^9 - x^25 + x^36 - x^49 + x^100 - x^121 - x^169 + ...

MATHEMATICA

Table[Times @@ Apply[Times, FactorInteger[n] /. {p_, e_} /; p > 1 :> If[e == 2, -1, 0]], {n, 105}] (* Michael De Vlieger, Jul 29 2017 *)

PROG

(PARI) {a(n) = if( n<1, 0, direuler( p=2, n, 1 - X^2 )[n])};

(PARI) {a(n) = my(A, p, e); if( n<1, 0, A = factor(n); prod(k=1, matsize(A)[1], [p, e] = A[k, ]; -(e==2)))};

(Scheme) (define (A271102 n) (if (= 1 n) n (* (if (= 2 (A067029 n)) -1 0) (A271102 (A028234 n))))) ;; Antti Karttunen, Jul 28 2017

CROSSREFS

Cf. A227291 (gives the absolute values).

Sequence in context: A014504 A014999 A227291 * A065803 A304362 A230135

Adjacent sequences:  A271099 A271100 A271101 * A271103 A271104 A271105

KEYWORD

sign,mult

AUTHOR

Michael Somos, Mar 30 2016

EXTENSIONS

More terms from Antti Karttunen, Jul 28 2017

STATUS

approved

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Last modified February 19 16:02 EST 2019. Contains 320311 sequences. (Running on oeis4.)