A175192 a(n) = characteristic function of numbers k such that A000203(m) = k has solution, where A000203(m) = sums of divisors of m.

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

Offset

1,1

Comments

a(n) = 1 if A000203(m) = n for some m, else 0.

a(n) = 1 for n such that A054973(n) >= 1. a(n) = 0 for n such that A054973(n) = 0.

Links

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

Index entries for characteristic functions

Mathematica

nn = 200; t = Union[Select[DivisorSigma[1, Range[nn]], # <= nn &]]; t2 = Table[0, {200}]; t2[[t]] = 1; t2 (* T. D. Noe, Jan 24 2012 *)

Prog

(PARI)
up_to = 65537
v175192 = vector(up_to);
for(k=1, up_to, t=sigma(k); if(t<=up_to, v175192[t] = 1)); \\ See also code in A054973.
write_to_bfile(start_offset, vec, bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
write_to_bfile(1, v175192, "b175192_upto65537.txt");
\\ Antti Karttunen, Oct 20 2017

Crossrefs

Characteristic function of A002191.

Cf. A000203, A054973.

Sequence in context: A057078 A204418 A127245 * A088150 A365938 A117567

Adjacent sequences: A175189 A175190 A175191 * A175193 A175194 A175195

Keyword

nonn

Author

Jaroslav Krizek, Mar 01 2010

Extensions

More terms from Antti Karttunen, Oct 20 2017

Status

approved