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Search: id:A015219
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| A015219 |
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Odd tetrahedral numbers. |
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+0
5
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| 1, 35, 165, 455, 969, 1771, 2925, 4495, 6545, 9139, 12341, 16215, 20825, 26235, 32509, 39711, 47905, 57155, 67525, 79079, 91881, 105995, 121485, 138415, 156849, 176851, 198485, 221815, 246905, 273819, 302621, 333375, 366145, 400995, 437989
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Sum_{n>=0} 1/a(n) = (3/2)*log(2) [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Oct 20 2009]
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FORMULA
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(4n+1)(4n+2)(4n+3) / 6.
G.f.: (1+x)*(1+30*x+x^2)/(1-x)^4 [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Oct 20 2009]
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CROSSREFS
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Cf. A000292.
Adjacent sequences: A015216 A015217 A015218 this_sequence A015220 A015221 A015222
Sequence in context: A005339 A045614 A154074 this_sequence A033851 A101954 A005937
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KEYWORD
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nonn,easy,new
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AUTHOR
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Mohammad K. Azarian (ma3(AT)evansville.edu)
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EXTENSIONS
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More terms from Erich Friedman (erich.friedman(AT)stetson.edu).
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