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A000313 Number of permutations of length n with 3 consecutive ascending pairs.
(Formerly M3633 N1477)
8
0, 0, 0, 1, 4, 30, 220, 1855, 17304, 177996, 2002440, 24474285, 323060540, 4581585866, 69487385604, 1122488536715, 19242660629360, 348933579412440, 6673354706262864, 134252194678935321, 2834212998777523380, 62651024183503148470, 1447238658638922729580 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Temporary remark: there may be some issues with respect to the offset of this sequence in the formula and program sections. - Joerg Arndt, Nov 16 2014

REFERENCES

F. N. David, M. G. Kendall and D. E. Barton, Symmetric Function and Allied Tables, Cambridge, 1966, p. 263.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Todd Silvestri, Table of n, a(n) for n = 1..450 (first 100 terms by T. D. Noe)

FORMULA

a(n) = (n*(n+1)!/6)*sum((-1)^k/k!, k=0..n).

a(n) = A065087(n+2)/3. - Zerinvary Lajos, May 25 2007

E.g.f.: x^3/3!*exp(-x)/(1-x)^2. - Vladeta Jovovic, Jan 03 2003

a(n) = round( (exp(-1)*(n+1)!+(-1)^n)*n/6 ). - Mark van Hoeij, Oct 25 2011

G.f.: hypergeom([2, 4],[],x/(x+1))/(x+1)^4. - Mark van Hoeij, Nov 07 2011

a(1) = 0, a(n) = (n-2)*(n-1)*(!(n-2))/6 = (n-2)*(n-1)*A000166(n-2)/6, for n >= 2. - Todd Silvestri, Nov 15 2014

a(n) = hypergeom([4-n,2],[],1))*(-1)^n*A000292(n-3). - Peter Luschny, Nov 19 2014

MAPLE

series(hypergeom([2, 4], [], x/(x+1))/(x+1)^4, x=0, 30); # Mark van Hoeij, Nov 07 2011

a := n -> simplify(hypergeom([4-n, 2], [], 1))*(-1)^n*(n-1)*(n-2)*(n-3)/6: seq(a(n), n=1..23); # Peter Luschny, Nov 19 2014

MATHEMATICA

Table[(n*(n + 1)!/6)*Sum[(-1)^k/k!, {k, 0, n}], {n, -1, 25}] (* T. D. Noe, Jun 19 2012 *)

a[1]:=0; a[n_Integer/; n>=2]:=(n-2) (n-1) Subfactorial[n-2]/6 (* Todd Silvestri, Nov 15 2014 *)

PROG

(Sage)

a = lambda n: (n-2)*(n-1)*sloane.A000166(n-2)/6 if n>2 else 0

[a(n) for n in range(1, 24)] # Peter Luschny, Nov 19 2014

CROSSREFS

Cf. A010027, A000255, A000166, A000274, A001260, A001261.

A diagonal in triangle A010027.

Sequence in context: A134093 A007905 A084976 * A082144 A220727 A137971

Adjacent sequences:  A000310 A000311 A000312 * A000314 A000315 A000316

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Vladeta Jovovic, Jan 03 2003

Formula added by Sean A. Irvine, Nov 11 2010

Name clarified and offset changed by N. J. A. Sloane, Apr 12 2014

STATUS

approved

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Last modified June 27 19:44 EDT 2017. Contains 288790 sequences.