login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A118198 Triangle read by rows: T(n,k) is the number of partitions of n having k parts equal to the size of the Durfee square (0<=k<=n). 1
1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 2, 0, 1, 1, 2, 2, 1, 0, 1, 2, 3, 2, 2, 1, 0, 1, 3, 4, 3, 2, 1, 1, 0, 1, 5, 6, 4, 2, 2, 1, 1, 0, 1, 7, 8, 5, 4, 2, 1, 1, 1, 0, 1, 10, 11, 8, 5, 2, 2, 1, 1, 1, 0, 1, 13, 15, 11, 7, 3, 2, 1, 1, 1, 1, 0, 1, 18, 20, 16, 9, 5, 2, 2, 1, 1, 1, 1, 0, 1, 23, 27, 21, 13, 6, 3, 2, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,13

COMMENTS

Row sums yield the partition numbers (A000041). T(n,0)=A118199(n)

LINKS

Table of n, a(n) for n=0..98.

FORMULA

G.f.=G(t,x)=1+sum(x^(k^2)*P(k-1)sum(t^(k-j)*x^j*P(j), j=0..k)/(1-tx^k), k=1..infinity), where P(m)=1/product(1-x^i,i=1..m).

EXAMPLE

T(4,0)=1 because [4] has Durfee square of size 1 and there is no part equal to 1; T(4,1)=1 because [3,1] has Durfee square of size 1 and there is 1 part equal to 1; T(4,2)=2 because [2,2] has Durfee square of size 2 and there are 2 parts equal to 2 and [2,1,1] has Durfee square of size 1 and there are 2 parts equal to 1; T(4,3)=0 because obviously no partition of 4 can have exactly 3 parts of the same size; T(4,4)=1 because [1,1,1,1] has Durfee square of size 1 and there are 4 parts equal to 1.

Triangle starts:

1;

0,1;

1,0,1;

1,1,0,1;

1,1,2,0,1;

1,2,2,1,0,1;

MAPLE

g:=1+sum(x^(k^2)*sum(t^(k-j)*x^j/product(1-x^i, i=1..j), j=0..k)/(1-t*x^k)/product(1-x^i, i=1..k-1), k=1..20): gser:=simplify(series(g, x=0, 30)): P[0]:=1: for n from 1 to 13 do P[n]:=sort(coeff(gser, x^n)) od: for n from 0 to 13 do seq(coeff(P[n], t, p), p=0..n) od; # yields sequence in triangular form

CROSSREFS

Cf. A000041, A118199.

Sequence in context: A030218 A281388 A127440 * A290885 A059881 A096568

Adjacent sequences:  A118195 A118196 A118197 * A118199 A118200 A118201

KEYWORD

nonn,tabl

AUTHOR

Emeric Deutsch, Apr 14 2006

EXTENSIONS

Keyword tabl added by Michel Marcus, Apr 09 2013

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 April 21 20:59 EDT 2019. Contains 322328 sequences. (Running on oeis4.)