The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A052656 E.g.f. x*(1+2x-4x^2)/(1-2x). 0
 0, 1, 8, 24, 192, 1920, 23040, 322560, 5160960, 92897280, 1857945600, 40874803200, 980995276800, 25505877196800, 714164561510400, 21424936845312000, 685597979049984000, 23310331287699456000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Table of n, a(n) for n=0..17. INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 603 FORMULA E.g.f.: x*(-2*x+4*x^2-1)/(-1+2*x) Recurrence: {a(1)=1, a(0)=0, (-2*n-2)*a(n)+a(n+1)=0, a(2)=8, a(3)=24} 2^(n-1)*n!, n>2. MAPLE spec := [S, {S=Prod(Z, Union(Z, Z, Sequence(Union(Z, Z))))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20); MATHEMATICA With[{nn=20}, CoefficientList[Series[x (1+2x-4x^2)/(1-2x), {x, 0, nn}], x] Range[ 0, nn]!] (* Harvey P. Dale, Jan 06 2022 *) CROSSREFS Sequence in context: A061027 A226962 A221784 * A094061 A182589 A002268 Adjacent sequences: A052653 A052654 A052655 * A052657 A052658 A052659 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 2 13:50 EST 2023. Contains 367524 sequences. (Running on oeis4.)