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A002699 a(n) = n*2^(2*n-1).
(Formerly M2090 N0825)
8
0, 2, 16, 96, 512, 2560, 12288, 57344, 262144, 1179648, 5242880, 23068672, 100663296, 436207616, 1879048192, 8053063680, 34359738368, 146028888064, 618475290624, 2611340115968, 10995116277760, 46179488366592, 193514046488576 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Right side of binomial sum Sum(i * binomial(2*n, i), i=1..n) - Yong Kong (ykong(AT)curagen.com), Dec 26 2000

Coefficients of shifted Chebyshev polynomials.

Starting with offset 1 = 4th binomial transform of [2, 8, 0, 0, 0,...]. - Gary W. Adamson, Jul 21 2009

Let P(A) be the power set of an n-element set A and B be the Cartesian product of P(A) with itself. Then a(n) = the sum of the size of the symmetric difference of x and y for every (x,y) of B. - Ross La Haye, Jan 04 2013

It's the relation [27] with T(n) in the document of Ross. Following the last comment of Ross, A002697 is the similar sequence when replacing "symmetric difference" by "intersection" and A212698 is the similar  sequence when replacing "symmetric difference" by union. - Bernard Schott, Jan 04 2013

If Delta = Symmetric difference, here, X Delta Y and Y Delta X are considered as two distinct Cartesian products, if we want to consider that X Delta Y = X Delta Y is the same Cartesian product, see A002697. - Bernard Schott, Jan 15 2013

REFERENCES

C. Lanczos, Applied Analysis. Prentice-Hall, Englewood Cliffs, NJ, 1956, p. 518.

A. P. Prudnikov, Yu. A. Brychkov and O.I. Marichev, "Integrals and Series", Volume 1: "Elementary Functions", Chapter 4: "Finite Sums", New York, Gordon and Breach Science Publishers, 1986-1992.

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

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Ross La Haye, Binary Relations on the Power Set of an n-Element Set, Journal of Integer Sequences, Vol. 12 (2009), Article 09.2.6.

C. Lanczos, Applied Analysis (Annotated scans of selected pages)

Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992.

Simon Plouffe, 1031 Generating Functions and Conjectures, Université du Québec à Montréal, 1992.

Index entries for sequences related to Chebyshev polynomials.

Index entries for linear recurrences with constant coefficients, signature (8,-16).

FORMULA

a(n) = 2 * A002697(n). - Bernard Schott, Jan 04 2013

a(n) = A212698(n) - A002697(n)

a(n) = 8*a(n-1)-16*a(n-2) with n>1, a(0)=0, a(1)=2. - Vincenzo Librandi, Mar 20 2013

MAPLE

A002699 := n->n*2^(2*n-1);

A002699:=2*z/(4*z-1)**2; # conjectured by Simon Plouffe in his 1992 dissertation

MATHEMATICA

Table[(n 2^(2 n - 1)), {n, 0, 30}] (* Vincenzo Librandi, Mar 20 2013 *)

LinearRecurrence[{8, -16}, {0, 2}, 30] (* Harvey P. Dale, Dec 20 2015 *)

PROG

(MAGMA) [n*2^(2*n-1): n in [0..30]]; /* or */ I:=[0, 2]; [n le 2 select I[n] else 8*Self(n-1)-16*Self(n-2): n in [1..30]]; // Vincenzo Librandi, Mar 20 2013

(PARI) a(n)=n*2^(2*n-1) \\ Charles R Greathouse IV, Oct 07 2015

CROSSREFS

Found in A053125 and A053124.

Cf. A002697, A212698.

Sequence in context: A141243 A163229 A038749 * A005058 A082639 A207301

Adjacent sequences:  A002696 A002697 A002698 * A002700 A002701 A002702

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified January 18 16:27 EST 2020. Contains 331011 sequences. (Running on oeis4.)