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Search: id:A133694
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| 1, 7, 16, 28, 43, 61, 82, 106, 133, 163, 196, 232, 271, 313, 358, 406, 457, 511, 568, 628, 691, 757, 826, 898, 973, 1051, 1132, 1216, 1303, 1393, 1486, 1582, 1681, 1783, 1888, 1996, 2107, 2221, 2338, 2458, 2581, 2707, 2836, 2968, 3103, 3241, 3382, 3526, 3673
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Contribution from Gary W. Adamson (qntmpkt(AT)yahoo.com), May 01 2009: (Start)
Equals (1, 2, 3, 4,...) convolved with (1, 5, 3, 3, 3,...). a(4) = 28 =
(1, 2, 3, 4) dot (3, 3, 5, 1) = (3 + 6 + 15 + 4). (End)
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FORMULA
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a(n) = 3*T(n) - 2, where T(n) = n-th Triangular number of A000217. A133694 = binomial transform of [1, 6, 3, 0, 0, 0,...].
Row sums of triangle A133981 - Gary W. Adamson (qntmpkt(AT)yahoo.com), Sep 30 2007
a(n)=a(n-1)+3n (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 08 2009]
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EXAMPLE
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a(3) = 16 = 3*T(3) - 2 = 3*6 - 2.
a(4) = 28 = (1, 3, 3, 1) dot (1, 6, 3, 0) = (1, 18, 9, 0) = 28.
n=2, a(2)=1+6=7; n=3, a(3)=7+9=16; n=4, a(4)=16+12=28 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 08 2009]
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MATHEMATICA
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s=1; lst={}; Do[s+=n-3; If[s>0, AppendTo[lst, s]], {n, 0, 6!, 3}]; lst [From Vladmir Orlovsky (4vladimir(AT)gmail.com), Nov 04 2008]
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CROSSREFS
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Cf. A000217.
Cf. A133981.
Sequence in context: A052221 A119461 A028560 this_sequence A024627 A140511 A121470
Adjacent sequences: A133691 A133692 A133693 this_sequence A133695 A133696 A133697
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KEYWORD
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nonn
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AUTHOR
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Gary W. Adamson (qntmpkt(AT)yahoo.com), Sep 20 2007
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EXTENSIONS
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More terms and Mathematica program Vladmir Orlovsky (4vladimir(AT)gmail.com), Nov 04 2008
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