login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A181805 Number of divisors of A181804(n) that are highly composite (A002182). 4
1, 2, 3, 3, 5, 6, 6, 7, 6, 7, 8, 8, 8, 10, 11, 14, 9, 9, 12, 14, 19, 15, 20, 21, 21, 20, 15, 22, 22, 22, 21, 23, 22, 17, 23, 23, 23, 24, 25, 24, 25, 23, 23, 25, 28, 25, 27, 27, 31, 22, 27, 26, 30, 18 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) = maximal number of members of A002182 that have a least common multiple of A181804(n). Also, a(n) = length of row A181804(n) in triangles A181802 and A181803.

4, 13 and 16 are the first three positive integers that appear nowhere in this sequence (and, therefore, nowhere in A181801).  It would be interesting to know whether there are others.

LINKS

Table of n, a(n) for n=1..54.

A. Flammenkamp, List of the first 1200 highly composite numbers

Eric Weisstein's World of Mathematics, Highly composite number

FORMULA

a(n) = A181801(A181804(n)).

EXAMPLE

A181804(10) = 72 has exactly seven divisors that are members of A002182 (namely, 1, 2, 4, 6, 12, 24 and 36). Hence, a(10) = 7.

CROSSREFS

A181806(m) is the m-th member of A181804 such that the value of a(n) increases to a record. See also A181807.

Sequence in context: A296834 A242642 A178041 * A212010 A328745 A003967

Adjacent sequences:  A181802 A181803 A181804 * A181806 A181807 A181808

KEYWORD

nonn,more

AUTHOR

Matthew Vandermast, Nov 27 2010

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 1 03:09 EST 2021. Contains 341732 sequences. (Running on oeis4.)