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0, 11, 44, 99, 176, 275, 396, 539, 704, 891, 1100, 1331, 1584, 1859, 2156, 2475, 2816, 3179, 3564, 3971, 4400, 4851, 5324, 5819, 6336, 6875, 7436, 8019, 8624, 9251, 9900, 10571, 11264, 11979, 12716
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refs;
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history;
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OFFSET
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0,2
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COMMENTS
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Number of edges of the complete tripartite graph of order 7n, K_n,n,5n - Roberto E. Martinez II, Jan 07 2002
Number of edges of the complete tripartite graph of order 6n, K_n,2n,3n - Roberto E. Martinez II, Jan 07 2002
11 times the squares. - Omar E. Pol, Dec 13 2008
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LINKS
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Table of n, a(n) for n=0..34.
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
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a(n) = A000290(n)*11. - Omar E. Pol, Dec 13 2008
a(n) = 22*n+a(n-1)-11 (with a(0)=0) - Vincenzo Librandi, Aug 05 2010
From Amiram Eldar, Feb 03 2021: (Start)
Sum_{n>=1} 1/a(n) = Pi^2/66.
Sum_{n>=1} (-1)^(n+1)/a(n) = Pi^2/132.
Product_{n>=1} (1 + 1/a(n)) = sqrt(11)*sinh(Pi/sqrt(11))/Pi.
Product_{n>=1} (1 - 1/a(n)) = sqrt(11)*sin(Pi/sqrt(11))/Pi. (End)
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EXAMPLE
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a(1)=22*1+0-11=11; a(2)=22*2+11-11=44; a(3)=22*3+44-11=99 - Vincenzo Librandi, Aug 05 2010
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MATHEMATICA
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Table[11*n^2, {n, 0, 35}] (* Amiram Eldar, Feb 03 2021 *)
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PROG
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(PARI) a(n)=11*n^2 \\ Charles R Greathouse IV, Jun 17 2017
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CROSSREFS
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Cf. A000290.
Sequence in context: A022703 A061976 A070930 * A248126 A253445 A172526
Adjacent sequences: A033581 A033582 A033583 * A033585 A033586 A033587
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane.
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STATUS
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approved
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