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A002801 a(n) = (2*n-1)*a(n-1) - (n-1)*a(n-2).
(Formerly M1882 N0744)
4
1, 1, 2, 8, 50, 418, 4348, 54016, 779804, 12824540, 236648024, 4841363104, 108748223128, 2660609220952, 70422722065040, 2005010410792832, 61098981903602192, 1984186236246187024, 68407835576255308576, 2495374564069015050880, 96019859122742736121376, 3886906732751071879958816, 165120572466718493379680192 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Row sums of A152148. [Paul Barry, Nov 26 2008]

REFERENCES

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).

Michael Z. Spivey and Laura L. Steil, The k-Binomial Transforms and the Hankel Transform, Journal of Integer Sequences, Vol. 9 (2006), Article 06.1.1.

J. J. Sylvester, Note on determinants..., Amer. J. Math., 2 (1879), circa p. 94.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..100

E. Lucas, Th\'{e}orie des Nombres. Gauthier-Villars, Paris, 1891, Vol. 1, p. 223.

FORMULA

Appears to be the BinomialMean transform of A007696 (see A075271). - John W. Layman, Oct 01 2002

E.g.f.: exp(x/2)*(1-2*x)^(-1/4). [From Paul Barry, Nov 26 2008]

a(n) = hypergeom([1/4, -n],[],-4)/(2^n) [From Mark van Hoeij, Jun 02 2010]

a(n) ~ n^(n-1/4) * exp(-n+1/4) * Gamma(3/4) * 2^n / sqrt(Pi). - Vaclav Kotesovec, Oct 08 2013

MATHEMATICA

nxt[{n_, a_, b_}]:={n+1, b, b*(2n+1)-a*n}; Transpose[NestList[nxt, {1, 1, 1}, 30]][[2]] (* Harvey P. Dale, Sep 04 2013 *)

a[n_] := HypergeometricPFQ[{1/4, -n}, {}, -4]/(2^n); Table[a[n], {n, 0, 22}] (* Jean-Fran├žois Alcover, Mar 17 2014, after Mark van Hoeij *)

PROG

(Maxima) a(n):=coeff(taylor(exp(x/2)/(1-2*x)^(1/4), x, 0, n), x, n)*n!;

makelist(a(n), n, 0, 12); [Emanuele Munarini, Jul 07 2011]

(PARI)  x='x+O('x^66); /* that many terms */

Vec(serlaplace(exp(x/2)*(1-2*x)^(-1/4))) /* show terms */ /* Joerg Arndt, Jul 10 2011 */

CROSSREFS

Sequence in context: A120956 A000557 A193352 * A233436 A225052 A089104

Adjacent sequences:  A002798 A002799 A002800 * A002802 A002803 A002804

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from John W. Layman, Oct 01 2002

STATUS

approved

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Last modified April 20 23:07 EDT 2014. Contains 240824 sequences.