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0, 5, 20, 45, 80, 125, 180, 245, 320, 405, 500, 605, 720, 845, 980, 1125, 1280, 1445, 1620, 1805, 2000, 2205, 2420, 2645, 2880, 3125, 3380, 3645, 3920, 4205, 4500, 4805, 5120, 5445, 5780, 6125, 6480, 6845, 7220, 7605, 8000, 8405, 8820, 9245, 9680
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Number of edges of the complete bipartite graph of order 6n, K_n,5n - Roberto E. Martinez II (remartin(AT)fas.harvard.edu), Jan 07 2002
Number of edges of the complete tripartite graph of order 4n, K_n,n,2n - Roberto E. Martinez II (remartin(AT)fas.harvard.edu), Jan 07 2002
a(n+1) -a(n) : 5, 15, 25, 35, 45, ... (see A017329). - DELEHAM Philippe, Dec 08 2011
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REFERENCES
| L. Hogben, Choice and Chance by Cardpack and Chessboard. Vol. 1, Chanticleer Press, NY, 1950, p. 36.
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
| G.f.: 5*x*(1+x)/(1-x)^3. a(n) = 4*A000217(n)+A000567(n). - Bruno Berselli, Feb 11 2011
a(n) = a(n-1)+5*(2*n-1) (with a(0)=0). - Vincenzo Librandi, Nov 17 2010
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MAPLE
| seq(bell(3, j)*(j-2)^2, j = 2 .. 46) ; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Nov 29 2007
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MATHEMATICA
| s=0; lst={s}; Do[s+=n++ +5; AppendTo[lst, s], {n, 0, 7!, 10}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 16 2008]
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PROG
| (PARI) a(n)=5*n^2
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CROSSREFS
| Central column of A055096.
a(n) = A000290(n)*5. [From Omar E. Pol, Dec 11 2008]
Cf. numbers of the form n*(d*n+10-d)/2: A008587, A056000, A028347, A140090, A014106, A028895, A045944, A186029, A007742, A022267, A022268, A049452, A186030, A135703, A152734, A139273.
Cf. A185019.
Sequence in context: A031304 A178977 A061188 * A168011 A160749 A147002
Adjacent sequences: A033426 A033427 A033428 * A033430 A033431 A033432
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KEYWORD
| nonn,easy
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AUTHOR
| Jeff Burch (jmburch(AT)osprey.smcm.edu)
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EXTENSIONS
| Better description from N. J. A. Sloane, May 15 1998
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