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A294937
Characteristic function for abundant numbers (A005101): a(n) = 1 if A001065(n) > n, 0 otherwise.
17
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1
OFFSET
1
FORMULA
a(n) = 1 if A033880(n) > 0, 0 otherwise.
a(n) = 1 - A294935(n).
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = A302991. - Amiram Eldar, Jul 25 2022
MATHEMATICA
a[n_] := If[DivisorSigma[1, n] > 2*n, 1, 0]; Array[a, 100] (* Amiram Eldar, Jul 25 2022 *)
PROG
(PARI) a(n) = sigma(n) > 2*n; \\ Michel Marcus, Jul 25 2022
CROSSREFS
Cf. A005101 (positions of ones), A263837 (of zeros).
Sequence in context: A294930 A353472 A359475 * A363131 A355447 A045701
KEYWORD
nonn
AUTHOR
Antti Karttunen, Nov 12 2017
STATUS
approved