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1, 2, 6, 13, 23, 36, 52, 71, 93, 118, 146, 177, 211, 248, 288, 331, 377, 426, 478, 533, 591, 652, 716, 783, 853, 926, 1002, 1081, 1163, 1248, 1336, 1427, 1521, 1618, 1718, 1821, 1927, 2036, 2148, 2263, 2381, 2502, 2626, 2753, 2883, 3016, 3152, 3291
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Equals left border of triangle A033292
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LINKS
| Index entries for sequences related to linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
| a(n) = A000326(n+1) - 3*n. (A000326 are the pentagonal numbers).
Equals binomial transform of [1, 1, 3, 0, 0, 0,...].
a(n) = (3*n^2-n+2)/2 = A027599(n+1)/2. - R. J. Mathar, Sep 03 2008
a(n) = a(n-1)+3*n-2 (with a(0)=1) [From Vincenzo Librandi, Nov 25 2010]
a(n) = 2*a(n-1)-a(n-2)+3.
O.g.f.: (1-x+3*x^2)/((1-x)^3). [From Eric Werley, Jun 27 2011]
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CROSSREFS
| a(n) = A000326(n+1) - 3n.
Cf. A033292.
Sequence in context: A026052 A049616 A064960 * A180773 A011891 A184533
Adjacent sequences: A143686 A143687 A143688 * A143690 A143691 A143692
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KEYWORD
| nonn,easy
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AUTHOR
| Gary W. Adamson (qntmpkt(AT)yahoo.com), Aug 29 2008
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EXTENSIONS
| Corrected index of A000326 in definition, formula and example. - R. J. Mathar, Sep 03 2008
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