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A174897 a(n) = characteristic function of numbers k such that A007955(m) = k has solution for some m, where A007955(m) = product of divisors of m. 4
1, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) = characteristic function of numbers from A174895(n).

a(n) = 1 if A007955(m) = n for any m, else 0.

LINKS

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

Index entries for characteristic functions

FORMULA

a(n) = 1 - A174898(n).

MATHEMATICA

Block[{nn = 105, t}, t = ConstantArray[0, nn]; ReplacePart[t, Map[# -> 1 &, TakeWhile[Sort@ Array[Times @@ Divisors@ # &, nn], # <= 105 &]]]] (* Michael De Vlieger, Oct 20 2017 *)

PROG

(PARI)

up_to = 65537;

v174897 = vector(up_to);

A007955(n) = if(issquare(n, &n), n^numdiv(n^2), n^(numdiv(n)/2)); \\ This function from Charles R Greathouse IV, Feb 11 2011

for(k=1, up_to, t=A007955(k); if(t<=up_to, v174897[t] = 1));

write_to_bfile(start_offset, vec, bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }

write_to_bfile(1, v174897, "b174897_upto65537.txt");

\\ Antti Karttunen, Oct 20 2017

CROSSREFS

Cf. A007955, A174895, A174898.

Sequence in context: A214330 A266591 A132194 * A316441 A190938 A189166

Adjacent sequences:  A174894 A174895 A174896 * A174898 A174899 A174900

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Apr 01 2010

EXTENSIONS

Name edited and more terms added by Antti Karttunen, Oct 20 2017

STATUS

approved

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Last modified February 25 22:44 EST 2020. Contains 332270 sequences. (Running on oeis4.)