A245656 Characteristic function of arithmetic numbers, cf. A003601.

1, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1

Offset

1

Comments

a(A003601(n)) = 1; a(A049642(n)) = 0.

Links

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

Antti Karttunen, Data supplement: n, a(n) computed for n = 1..100000

Wikipedia, Arithmetic number

Index entries for characteristic functions

Formula

a(n) = A000007(A054025(n)).

Mathematica

a[n_] := Boole[IntegerQ[Mean[Divisors[n]]]];
Array[a, 105] (* Jean-François Alcover, Dec 02 2021 *)

Prog

(Haskell)
a245656 = (0 ^) . a054025 :: (Integral a, Integral t) => a -> t
(PARI) A245656(n) = !(sigma(n)%numdiv(n)); \\ Antti Karttunen, Dec 24 2018

Crossrefs

Cf. A003601, A049642, A054025, A000007, A069928 (partial sums).

Cf. also A176801.

Sequence in context: A004593 A094934 A245837 * A354032 A285625 A283966

Adjacent sequences: A245653 A245654 A245655 * A245657 A245658 A245659

Keyword

nonn

Author

Reinhard Zumkeller, Jul 28 2014

Extensions

More terms from Antti Karttunen, Dec 24 2018

Status

approved