This site is supported by donations to The OEIS Foundation.

"Email this user" was broken Aug 14 to 9am Aug 16. If you sent someone a message in this period, please send it again.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A163843 Row sums of triangle A163840. 2
 1, 3, 10, 41, 116, 427, 1240, 4181, 12472, 40091, 121364, 380701, 1160186, 3593969, 10979532, 33785469, 103258800, 316532947, 966976444, 2957131673, 9026437602, 27558146133, 84043120308, 256263107177, 780817641926 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 Peter Luschny, Swinging Factorial. FORMULA a(n) = Sum_{k=0..n} Sum_{i=k..n} binomial(n-k,n-i)*i\$ where i\$ denotes the swinging factorial of i (A056040). MAPLE swing := proc(n) option remember; if n = 0 then 1 elif irem(n, 2) = 1 then swing(n-1)*n else 4*swing(n-1)/n fi end: a := proc(n) local i, k; add(add(binomial(n-k, n-i)*swing(i), i=k..n), k=0..n) end: MATHEMATICA sf[n_] := n!/Quotient[n, 2]!^2; t[n_, k_] := Sum[Binomial[n - k, n - i]*sf[i], {i, k, n}]; Table[Sum[t[n, k], {k, 0, n}], {n, 0, 50}] (* G. C. Greubel, Aug 06 2017 *) CROSSREFS Cf. A056040, A163840. Sequence in context: A137781 A208125 A213108 * A149056 A149057 A149058 Adjacent sequences:  A163840 A163841 A163842 * A163844 A163845 A163846 KEYWORD nonn,changed AUTHOR Peter Luschny, Aug 06 2009 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.