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A062189 a(n) = 2 * 3^(n-2)*n*(1+2*n). 2
0, 2, 20, 126, 648, 2970, 12636, 51030, 198288, 747954, 2755620, 9959598, 35429400, 124357194, 431530092, 1482720390, 5050815264, 17075199330, 57338232372, 191385721566, 635369601960, 2099044209402, 6903833113980 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Define a triangle with left (first) column T(n,0)=n^2 for n=0,1,2,3.. and the remaining terms T(r,c) = T(r-1,c-1) + 2*T(r,c-1). Then T(n,n) = a(n) on the diagonal. T(n,1) = A056105(n).  - J. M. Bergot, Jan 26 2013

LINKS

Harry J. Smith, Table of n, a(n) for n = 0..200

Index entries for linear recurrences with constant coefficients, signature (9,-27,27).

FORMULA

a(n) = A002943(n)*A000244(n-2). Binomial transform of A007758.

G.f.: 2*x*(1+x)/(1-3*x)^3. - Ralf Stephan, Mar 13 2003

a(n) = 2*A077616(n). - R. J. Mathar, Jan 29 2013

E.g.f.: 2*x*(1+2*x)*exp(3*x). - G. C. Greubel, Jun 06 2019

MATHEMATICA

Table[2*3^(n-2)*n*(1+2*n), {n, 0, 30}] (* G. C. Greubel, Jun 06 2019 *)

PROG

(PARI) { for (n=0, 200, write("b062189.txt", n, " ", n*(4*n + 2)*3^(n - 2)) ) } \\ Harry J. Smith, Aug 02 2009

(MAGMA) [2*3^(n-2)*n*(1+2*n): n in [0..30]]; // G. C. Greubel, Jun 06 2019

(Sage) [2*3^(n-2)*n*(1+2*n) for n in (0..30)] # G. C. Greubel, Jun 06 2019

(GAP) List([0..30], n-> 2*3^(n-2)*n*(1+2*n)) # G. C. Greubel, Jun 06 2019

CROSSREFS

Sequence in context: A196797 A196585 A197042 * A203605 A094254 A093647

Adjacent sequences:  A062186 A062187 A062188 * A062190 A062191 A062192

KEYWORD

nonn,easy,changed

AUTHOR

Henry Bottomley, Jun 13 2001

STATUS

approved

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Last modified June 17 22:17 EDT 2019. Contains 324200 sequences. (Running on oeis4.)