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Search: id:A138621
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| A138621 |
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a(1)=2. For n >=2, a(n) = p(n) *(floor(a(n-1)/p(n)) +2), where p(n) is the nth prime. |
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1
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| 2, 6, 15, 28, 44, 65, 85, 114, 138, 174, 217, 259, 328, 387, 470, 530, 590, 671, 804, 923, 1022, 1106, 1245, 1335, 1455, 1616, 1751, 1926, 2071, 2260, 2413, 2620, 2877, 3058, 3278, 3473, 3768, 4075, 4342, 4671, 5012, 5249, 5539, 5790, 6107, 6368, 6752, 7136
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(n) is the next-to-least multiple of the nth prime that is > a(n-1).
If we instead had the sequence where a(1)=2 and where a(n) is the least multiple of the nth prime that is > a(n-1), then a(n) would equal the nth prime for all positive integers n.
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MAPLE
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A138621 := proc(n) option remember ; local a ; if n = 1 then RETURN(2) ; fi ; p := ithprime(n) ; p*(floor(A138621(n-1)/p)+2) ; end: seq(A138621(n), n=1..80) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 20 2008
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MATHEMATICA
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a = {2}; Do[AppendTo[a, Prime[n]*(Floor[a[[ -1]]/Prime[n]] + 2)], {n, 2, 60}]; a - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), May 18 2008
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CROSSREFS
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Sequence in context: A050508 A033298 A091766 this_sequence A033286 A098651 A087427
Adjacent sequences: A138618 A138619 A138620 this_sequence A138622 A138623 A138624
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), May 14 2008
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com) and R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 18 2008
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