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A021029

Expansion of 1/((1-x)*(1-2*x)*(1-3*x)*(1-6*x)).

1, 12, 97, 672, 4333, 26964, 164809, 998184, 6017605, 36192156, 217414561, 1305276336, 7834033117, 47011340388, 282089500153, 1692601439928, 10155802087669, 60935393132460, 365614101138385

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OFFSET

0,2

COMMENTS

a(n) is the area of the (n+3)-gon with vertices (2^k,3^k) for 0 <= k <= n+2. - J. M. Bergot and Robert Israel, Dec 05 2020

LINKS

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

Index entries for linear recurrences with constant coefficients, signature (12,-47,72,-36).

FORMULA

G.f.: 1/((1-x)*(1-2*x)*(1-3*x)*(1-6*x)).

a(n) = (-1+5*2^(n+2)-5*3^(n+2)+6^(n+2))/10. - Bruno Berselli, Sep 02 2011

MAPLE

seq(-1/10 + 2^(n+1) - (9*3^n)/2 + (18*6^n)/5, n=0..40); # Robert Israel, Dec 05 2020

MATHEMATICA

CoefficientList[Series[1/((1 - x)(1 - 2x)(1 - 3x)(1 - 6x)), {x, 0, 30}], x] (* Harvey P. Dale, Mar 14 2011 *)

PROG

(Magma) [(-1+5*2^(n+2)-5*3^(n+2)+6^(n+2))/10: n in [0..20]]; // Vincenzo Librandi, Sep 02 2011

CROSSREFS

Cf. A001240 (first differences).

Sequence in context: A121791 A016753 A078605 * A270496 A128594 A166793

Adjacent sequences: A021026 A021027 A021028 * A021030 A021031 A021032

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

URL: https://oeis.org/A021029

⇱ A021029 - OEIS