A343219 a(n) = 1 if A003415(sigma(k)) > k, otherwise 0.

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

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for characteristic functions

Index entries for sequences related to sigma(n)

Mathematica

Array[Boole[If[#2 < 2, 0, #2 Total[#2/#1 & @@@ FactorInteger[#2]]] > #1] & @@ {#, DivisorSigma[1, #]} &, 105] (* Michael De Vlieger, Apr 08 2021 *)

Prog

(PARI)
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A343219(n) = (A003415(sigma(n))>n);

Crossrefs

Cf. A000203, A003415, A343220, A343225.

Characteristic function of A343218.

Sequence in context: A308901 A286804 A188071 * A189640 A289057 A106138

Adjacent sequences: A343216 A343217 A343218 * A343220 A343221 A343222

Keyword

nonn

Author

Antti Karttunen, Apr 08 2021

Status

approved