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A303933
a(n) is the number of odd primitive abundant numbers with n distinct prime divisors.
1
0, 0, 8, 576, 3913172
OFFSET
1,3
COMMENTS
The 6th term is possibly 59687996404445, but this is at present unverified. - Jacob Liddy, Oct 16 2018
REFERENCES
Valdas Diciunas, On the number of odd primitive abundant numbers with five and six distinct prime factors, Vilnius Conference in Combinatorics and Number Theory, page 12, 2017.
LINKS
L. E. Dickson, Finiteness of the odd perfect and primitive abundant numbers with n distinct prime factors, American Journal of Mathematics 35 (1913), pp. 413-422.
Jacob Liddy, OPANS (Odd Primitive Abundant NumberS), 2018. The downloadable file is a Zip-archive, 640 Megabytes, uncompresses to 10 Gigabytes.
CROSSREFS
Cf. A005231 (odd abundant), A006038 (odd primitive abundant).
Row lengths of A188439.
Sequence in context: A248706 A325292 A326552 * A188780 A015023 A225168
KEYWORD
hard,more,nonn
AUTHOR
Jacob Liddy, May 02 2018
STATUS
approved