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A347244 Characteristic function of A347242. 7
0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1

LINKS

Table of n, a(n) for n=1..121.

Index entries for characteristic functions

FORMULA

a(1) = 0, and for n > 1, a(n) = 1 if for some k > 0, A006530(A000593^(k)(n)) >= A006530(n), otherwise 0. Here A000593^(k) means the k-fold application of the sum of odd divisors.

For n >= 1, a(n) = 0 iff A347245(n) = 0.

PROG

(PARI)

A000265(n) = (n >> valuation(n, 2));

A000593(n) = sigma(A000265(n));

A006530(n) = if(1==n, n, my(f=factor(n)); f[#f~, 1]);

A347244(n) = { my(gpf=A006530(n)); while(n>1, n = A000593(n); if(A006530(n)>=gpf, return(1))); (0); };

CROSSREFS

Cf. A000593, A006530, A347240, A347242, A347243, A347245, A347246.

Sequence in context: A037816 A297038 A044939 * A037824 A025461 A169674

Adjacent sequences:  A347241 A347242 A347243 * A347245 A347246 A347247

KEYWORD

nonn

AUTHOR

Antti Karttunen, Aug 28 2021

STATUS

approved

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Last modified January 29 00:42 EST 2022. Contains 350670 sequences. (Running on oeis4.)