This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A052572 E.g.f. (1+2x-2x^2)/(1-x)^2. 5
 1, 4, 10, 36, 168, 960, 6480, 50400, 443520, 4354560, 47174400, 558835200, 7185024000, 99632332800, 1482030950400, 23538138624000, 397533007872000, 7113748561920000, 134449847820288000, 2676192208994304000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS a(n) equals the permanent of the (n+1) X (n+1) matrix whose entry directly below the entry in the top right corner is 3, and all of whose other entries are 1. [From John M. Campbell, May 25 2011] In factorial base representation (A007623) the terms are written as: 1, 20, 120, 1200, 12000, 120000, ... From a(2) = 10 = "120" onward each term begins always with "120", followed by n-2 additional zeros. - Antti Karttunen, Sep 24 2016 LINKS INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 515 FORMULA E.g.f.: -(-2*x+2*x^2-1)/(-1+x)^2 Recurrence: {a(0)=1, a(1)=4, a(2)=10, (-n^2-5*n-4)*a(n)+(n+3)*a(n+1)=0} a(n) = (n+3)*n! for n>0. For n <= 1, a(n) = (n+1)^2, for n > 1, a(n) = (n+1)! + 2*n! - Antti Karttunen, Sep 24 2016 MAPLE spec := [S, {S=Prod(Union(Z, Z, Sequence(Z)), Sequence(Z))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20); PROG (Scheme, two different implementations) (define (A052572 n) (if (zero? n) 1 (* (+ 3 n) (A000142 n)))) (define (A052572 n) (if (<= n 1) (* (+ 1 n) (+ 1 n)) (+ (A000142 (+ 1 n)) (* 2 (A000142 n))))) ;; Antti Karttunen, Sep 24 2016 CROSSREFS Essentially twice A038720. Cf. A000142. Row 7 of A276955, from a(2)=10 onward. Cf. sequences with formula (n + k)*n! listed in A282466. Sequence in context: A149185 A149186 A197552 * A079725 A154152 A025237 Adjacent sequences:  A052569 A052570 A052571 * A052573 A052574 A052575 KEYWORD easy,nonn AUTHOR encyclopedia(AT)pommard.inria.fr, Jan 25 2000 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.

Last modified March 18 22:11 EDT 2019. Contains 321305 sequences. (Running on oeis4.)