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A038846 4-fold convolution of A000302 (powers of 4); expansion of 1/(1-4*x)^4. 22
1, 16, 160, 1280, 8960, 57344, 344064, 1966080, 10813440, 57671680, 299892736, 1526726656, 7633633280, 37580963840, 182536110080, 876173328384, 4161823309824, 19585050869760, 91396904058880, 423311976693760 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Also minimal 3-covers of a labeled n-set that cover 3 points of that set uniquely (if offset is 3). Cf. A057524 for unlabeled case - Vladeta Jovovic, Sep 02 2000

Also convolution of A020918 with A000984 (central binomial coefficients)

Let M=[1,0,0,i;0,1,i,0;0,i,1,0;i,0,0,1], i=sqrt(-1). Then 1/det(I-xM)=1/(1-4x)^4. - Paul Barry, Apr 27 2005

With a different offset, number of n-permutations (n=4) of 5 objects u, v, w, z, x with repetition allowed, containing exactly three u's. Example: a(1)=16 because we have uuuv, uuvu, uvuu, vuuu, uuuw, uuwu, uwuu, wuuu, uuuz, uuzu, uzuu, zuuu, uuux, uuxu, uxuu and xuuu. - Zerinvary Lajos, May 19 2008

From A152818. a(n) = A006044/6. - Paul Curtz, Jan 07 2009

Also convolution of A000302 with A038845, also convolution of A002457 with A002802, also convolution of A002697. - Rui Duarte, Oct 08 2011

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..400

FORMULA

a(n) = binomial(n+3, 3)*4^n.

G.f.: 1/(1-4*x)^4.

a(n) = sum( a+b+c+d+e+f+g+h=n, f(a)*f(b)*f(c)*f(d)*f(e)*f(f)*f(g)*f(h)) with f(n)=A000984(n) . - Philippe Deléham, Jan 22 2004

MAPLE

seq(seq(binomial(i, j)*4^(i-3), j =i-3), i=3..22); # Zerinvary Lajos, Dec 03 2007

seq(binomial(n+3, 3)*4^n, n=0..19); # Zerinvary Lajos, May 19 2008

PROG

(Sage) [lucas_number2(n, 4, 0)*binomial(n, 3)/2^6 for n in xrange(3, 26)] # Zerinvary Lajos, Mar 11 2009

(MAGMA) [4^n*Binomial(n+3, 3): n in [0..30]]; // Vincenzo Librandi, Oct 15 2011

(PARI) Vec(1/(1-4*x)^4+O(x^99)) \\ Charles R Greathouse IV, Oct 03 2016

CROSSREFS

Cf. A000302, A020918, A000984, A038231.

Sequence in context: A121036 A224058 A073394 * A079767 A079768 A053410

Adjacent sequences:  A038843 A038844 A038845 * A038847 A038848 A038849

KEYWORD

easy,nonn

AUTHOR

Wolfdieter Lang

STATUS

approved

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Last modified March 21 07:23 EDT 2019. Contains 321367 sequences. (Running on oeis4.)