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Search: id:A090548
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| A090548 |
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Least number that ends an arithmetic progression of n numbers with the same number of divisors. |
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+0
4
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| 1, 3, 7, 23, 29, 157, 215, 1139, 1211, 2089, 5161, 5293, 6347, 10717, 14233, 28213, 31451, 72965, 119029, 121603, 124177, 611261, 632171, 2003171, 2012771
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OFFSET
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1,2
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COMMENT
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In the following triangle the n-th row contains the least set of n numbers in arithmetic progression with the same number of divisors. By "least" we mean that the largest term is minimized. Sequence contains the leading diagonal. In other words, largest of n numbers in arithmetic progression with the same tau function, or 0 if no such number exists.
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FORMULA
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a(n)=A090547(n)+(n-1)*A090549(n). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 28 2007
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EXAMPLE
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Triangle (A113470) begins:
1
2 3
3 5 7
5 11 17 23
5 11 17 23 29 ...
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CROSSREFS
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Leading diagonal of A113470.
Cf. A087309, A096003, A113470, A087308, A090547, A090549.
Adjacent sequences: A090545 A090546 A090547 this_sequence A090549 A090550 A090551
Sequence in context: A072584 A139513 A057191 this_sequence A087309 A127781 A122094
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Dec 09 2003
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EXTENSIONS
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Corrected and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 28 2007
More terms from David Wasserman (dwasserm(AT)earthlink.net), Jan 08 2006, May 11 2007
Edited by njas at the suggestion of Andrew Plewe, May 11 2007
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