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A175192 a(n) = characteristic function of numbers k such that A000203(m) = k has solution, where A000203(m) = sums of divisors of m. 7
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 (list; graph; refs; listen; history; text; internal format)
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: A260192 A057078 A127245 * A088150 A117567 A307183

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

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Last modified December 5 10:45 EST 2019. Contains 329751 sequences. (Running on oeis4.)