cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A284206 Tenth column of Euler's difference table in A068106.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 362880, 3265920, 33022080, 369774720, 4536362880, 60451816320, 869007242880, 13397819541120, 220448163358080, 3854801333416320, 71370457471716480, 1394586705296776320, 28676809138124407680, 618948032364173877120
Offset: 1

Views

Author

Enrique Navarrete, Mar 22 2017

Keywords

Comments

For n >= 10, this is the number of permutations of [n] that avoid substrings j(j+9), 1 <= j <= n-9.

Examples

			a(13)=4536362880 since this is the number of permutations in S13 that avoid substrings {1(10),2(11),3(12),4(13)}.
		

Crossrefs

Also 362880 times A176735.
Cf. A068106.

Programs

  • Mathematica
    Table[Sum[(-1)^j*Binomial[n - 9, j]*(n - j)!, {j, 0, n - 9}], {n, 22}] (* Michael De Vlieger, Apr 03 2017 *)

Formula

For n>=10: a(n) = Sum_{j=0..n-9} (-1)^j*binomial(n-9,j)*(n-j)!.
Note a(n)/n! ~ 1/e.