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Search: id:A048396
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| A048396 |
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Sum of consecutive noncubes. |
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+0
3
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| 0, 27, 315, 1638, 5670, 15345, 35217, 71820, 134028, 233415, 384615, 605682, 918450, 1348893, 1927485, 2689560, 3675672, 4931955, 6510483, 8469630, 10874430, 13796937, 17316585, 21520548, 26504100, 32370975, 39233727
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Relationship with triangular numbers: a(4) = 3.(first term + last term).Tria_n = 3.(28+63).6 = 3.(91).6 = 1638; a(5) = 3.(65+124).T4 = 3.(189).10 = 5670; ...
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FORMULA
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Formula = ( 6.n^5 + 15.n^4 + 18.n^3 + 12.n^2 + 3.n ) / 2.
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EXAMPLE
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Between 3^3 and 4^3 we have 28+29+.. ..+62+63 which is 1638 or a(4).
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CROSSREFS
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Cf. A048395, A048397, A000217.
Adjacent sequences: A048393 A048394 A048395 this_sequence A048397 A048398 A048399
Sequence in context: A086574 A125415 A119295 this_sequence A061181 A010832 A022719
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KEYWORD
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nonn,nice
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AUTHOR
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Patrick De Geest (pdg(AT)worldofnumbers.com), Mar 15 1999.
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