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A068314
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Smallest integer that can be expressed as the sum of consecutive odd numbers in exactly n ways.
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2
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1, 9, 45, 96, 144, 240, 768, 480, 720, 960, 2304, 1440, 5184, 3600, 2880, 3360, 36864, 5040, 3145728, 6720, 11520, 61440, 14400, 10080, 25920, 245760, 25200, 26880, 9437184, 20160, 12884901888, 30240, 184320, 3932160, 103680, 40320
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| The sequence continues: ?,30240,184320,3932160,103680,40320,?,129600,737280,60480,176400,80640,?,430080,100800 where ? is a value > 20000000. A value always exists since 3*(2^(i+1)) is an upper bound for the i-th term (i odd) and 5*3*(2^((i+2)/2)) is an upper bound for i even. Based on these limits, the bounds on the 31st, 37th and 43rd terms are 12884901888, 824633720832 and 52776558133248 respectively. - Larry Reeves (larryr(AT)acm.org), Dec 18 2002
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LINKS
| Don Reble, Table of n, a(n) for n = 1..2000
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EXAMPLE
| 45 = 45 = 13+15+17 = 5+7+9+11+13, 45 is the smallest number expressible in 3 ways, so a(3)=45.
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CROSSREFS
| Cf. A038548, A034178, A001227.
Sequence in context: A044492 A067536 A139609 * A152996 A188351 A060008
Adjacent sequences: A068311 A068312 A068313 * A068315 A068316 A068317
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KEYWORD
| nonn
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AUTHOR
| Naohiro Nomoto (n_nomoto(AT)yabumi.com), Feb 26 2002
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EXTENSIONS
| More terms from Larry Reeves (larryr(AT)acm.org), Dec 18 2002
Further terms from Don Reble (djr(AT)nk.ca), Sep 08 2006
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