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A086292 Number of divisors of 7-smooth numbers. 2
1, 2, 2, 3, 2, 4, 2, 4, 3, 4, 6, 4, 4, 5, 6, 6, 4, 8, 3, 4, 6, 8, 6, 4, 9, 8, 8, 6, 10, 3, 6, 8, 8, 12, 6, 7, 8, 12, 6, 10, 5, 12, 12, 12, 6, 9, 8, 12, 10, 16, 4, 12, 8, 8, 12, 15, 6, 12, 12, 10, 16, 6, 18, 8, 14, 9, 12, 16, 16, 12, 9, 20, 6, 6, 8, 18, 9, 16, 16, 18, 12, 18, 12, 14 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
a(n) = A000005(A002473(n)).
MATHEMATICA
DivisorSigma[0, Select[Range[500], Max[Transpose[FactorInteger[#]][[1]]] <= 7 &]] (* Amiram Eldar, Jan 06 2020 after G. C. Greubel at A086288 *)
CROSSREFS
Sequence in context: A193513 A218704 A144373 * A335708 A076640 A326198
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jul 15 2003
STATUS
approved

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Last modified March 28 05:39 EDT 2024. Contains 371235 sequences. (Running on oeis4.)