login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A285524 a(n) is the value d<n/2 maximizing the expression d!*(d + 1)!*(2^(n-2*d-1)*stirling2(n-d, d+1), for n>=4. 2
1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 14, 14, 14, 15, 15, 15, 16, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 22, 22, 22, 23, 23, 23, 24, 24, 24 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,4

COMMENTS

In case the maximum should turn out not to be unique, use the smallest value. - N. J. A. Sloane, Apr 22 2017

LINKS

Table of n, a(n) for n=4..78.

Robert Davis, Sarah A. Nelson, T. Kyle Petersen, Bridget E. Tenner, The pinnacle set of a permutation, arXiv:1704.05494 [math.CO], 2017.

MAPLE

f:= n -> max[index]([seq(d!*(d+1)!*2^(n-2*d-1)*Stirling2(n-d, d+1), d=1..n/2)]):

map(f, [$4..200]); # Robert Israel, Apr 20 2017

MATHEMATICA

a[n_] := MaximalBy[Table[{d, d! (d+1)! 2^(n-2d-1) StirlingS2[n-d, d+1]}, {d, 1, n/2}], Last][[All, 1]] // Min;

Table[a[n], {n, 4, 78}] (* Jean-Fran├žois Alcover, Sep 18 2018 *)

PROG

(PARI) half(n) = if (n % 2, n\2, n/2 - 1);

a(n) = {v = vector(half(n), d, d!*(d + 1)!*(2^(n-2*d-1)*stirling(n-d, d+1, 2))); w = vecsort(v, , 1); w[#w]; }

CROSSREFS

Cf. A285525, A285526.

Sequence in context: A034887 A192543 A082964 * A209356 A099741 A047743

Adjacent sequences:  A285521 A285522 A285523 * A285525 A285526 A285527

KEYWORD

nonn

AUTHOR

Michel Marcus, Apr 20 2017

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 January 27 17:58 EST 2020. Contains 331296 sequences. (Running on oeis4.)