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!)
A238003 Number of partitions of n not having depth 1; see Comments. 1
1, 1, 2, 3, 3, 5, 6, 11, 10, 17, 19, 30, 34, 50, 54, 89, 97, 126, 160, 215, 254, 339, 409, 549, 649, 838, 997, 1286, 1562, 1934, 2375, 2966, 3552, 4418, 5339, 6505, 7869, 9591, 11499, 13946, 16781, 20163, 24167, 28932, 34434, 41285, 49116, 58508, 69361 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

The depth of a partition is defined at A237685 as follows.  Suppose that P is a partition of n.  Let x(1), x(2), ..., x(k) be the distinct parts of P, and let m(i) be the multiplicity of x(i) in P.  Let f(P) be the partition [m(1)*x(1), m(2)*x(2), ... , x(k)*m(k)] of n.  Define c(0,P) = P, c(1,P) = f(P), ..., c(n,P) = f(c(n-1,P), and define d(P) = least n such that c(n,P) has no repeated parts; d(P) is the depth of P. Conjecture: lim(a(n)/A000041(n)) = 1.

LINKS

Table of n, a(n) for n=1..49.

FORMULA

a(n) = A000041(n) - A237685(n) for n >= 1.

EXAMPLE

The 11 partitions of 6 are partitioned by depth as follows:

depth 0:  6, 51, 42, 321

depth 1:  411, 33, 222, 2211, 21111, 11111

depth 2:  3111

Thus, a(6) = 5.

MATHEMATICA

z = 40; c[n_] := c[n] = Map[Length[FixedPointList[Sort[Map[Total, Split[#]], Greater] &, #]] - 2 &, IntegerPartitions[n]]

Table[Count[c[n], 1], {n, 1, z}] (* A237685 *)

Table[PartitionsP[n] - Count[c[n], 1], {n, 1, z}]  (* A238003 *)

(* Peter J. C. Moses, Feb 19 2014 *)

CROSSREFS

Cf. A237685, A000041.

Sequence in context: A241409 A018131 A121400 * A218932 A056878 A270520

Adjacent sequences:  A238000 A238001 A238002 * A238004 A238005 A238006

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Feb 19 2014

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 May 12 09:16 EDT 2021. Contains 343821 sequences. (Running on oeis4.)