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A327153
Number of divisors d of n such that sigma(d)*d is equal to n.
11
1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1
OFFSET
1,336
COMMENTS
a(n) tells how many times in total n occurs in A064987.
LINKS
FORMULA
a(n) = Sum_{d|n} [A000203(d)*d == n], where [ ] is the Iverson bracket.
EXAMPLE
336 has 20 divisors: [1, 2, 3, 4, 6, 7, 8, 12, 14, 16, 21, 24, 28, 42, 48, 56, 84, 112, 168, 336]. Only two of them, d=12 and d=14, satisfy sigma(d) = (336/d), thus a(336) = 2.
PROG
(PARI) A327153(n) = sumdiv(n, d, (n==d*sigma(d)));
CROSSREFS
Cf. A000203, A064987, A327165 (positions of nonzero terms).
Cf. also A324539.
Sequence in context: A353370 A355940 A348033 * A374197 A133943 A014084
KEYWORD
nonn
AUTHOR
Antti Karttunen, Sep 18 2019
STATUS
approved