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

 

Logo

Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A124007 Number of permutations of n distinct letters (ABCD...) each of which appears thrice with n-3 fixed points. 1
0, 0, 54, 216, 540, 1080, 1890, 3024, 4536, 6480, 8910, 11880, 15444, 19656, 24570 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..14.

EXAMPLE

Maple produces the following triangle - the entries in quotes give the sequence:

1

"0", 0, 0, 1

1, 0, 9, "0", 9, 0, 1

56, 216, 378, 435, 324, 189, "54", 27, 0, 1

13833, 49464, 84510, 90944, 69039, 38448, 16476, 5184, 1431, "216", 54, 0, 1

6699824, 23123880, 38358540, 40563765, 30573900, 17399178, 7723640, 2729295, 776520, 180100, 33372, 5355, "540", 90, 0, 1

etc...

MAPLE

p := (x, k)->k!^2*sum(x^j/((k-j)!^2*j!), j=0..k); R := (x, n, k)->p(x, k)^n; f := (t, n, k)->sum(coeff(R(x, n, k), x, j)*(t-1)^j*(n*k-j)!, j=0..n*k); for n from 0 to 6 do seq(coeff(f(t, n, 3), t, m)/3!^n, m=0..3*n); od;

CROSSREFS

Cf. A059058, A027468, A059073, A059072.

Sequence in context: A157428 A068380 A187299 * A221867 A245830 A102838

Adjacent sequences:  A124004 A124005 A124006 * A124008 A124009 A124010

KEYWORD

nonn

AUTHOR

Zerinvary Lajos, Nov 01 2006

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified August 23 01:19 EDT 2014. Contains 245976 sequences.