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A028994
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Even 10-gonal (or decagonal) numbers.
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6
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0, 10, 52, 126, 232, 370, 540, 742, 976, 1242, 1540, 1870, 2232, 2626, 3052, 3510, 4000, 4522, 5076, 5662, 6280, 6930, 7612, 8326, 9072, 9850, 10660, 11502, 12376, 13282, 14220, 15190, 16192, 17226, 18292, 19390, 20520, 21682, 22876
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| a(n) (n>=1) is also the Wiener index of the windmill graph D(5,n). The windmill graph D(m,n) is the graph obtained by taking n copies of the complete graph K_m with a vertex in common (i.e. a bouquet of n pieces of K_m graphs). The Wiener index of a connected graph is the sum of distances between all unordered pairs of vertices in the graph. The Wiener index of D(m,n) is (1/2)n(m-1)[(m-1)(2n-1)+1]. For the Wiener indices of D(3,n), D(4,n), and D(6,n) see A033991, A152743, and A180577, respectively. - Emeric Deutsch, Sep 21 2010
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REFERENCES
| Weisstein, Eric W. "Windmill Graph." http://mathworld.wolfram.com/WindmillGraph.html. [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Sep 21 2010]
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LINKS
| Eric Weisstein's World of Mathematics, Source
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FORMULA
| a(n) = 2*n*(8*n - 3). - Omar E. Pol, Aug 19 2011
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CROSSREFS
| Cf. A033991, A152743, A180577 [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Sep 21 2010]
Cf. A001107, A028993, A139273. - Omar E. Pol, Aug 19 2011
Sequence in context: A135242 A041186 A058827 * A092966 A050494 A200035
Adjacent sequences: A028991 A028992 A028993 * A028995 A028996 A028997
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KEYWORD
| nonn
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AUTHOR
| Patrick De Geest (pdg(AT)worldofnumbers.com)
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