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Search: id:A126695
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| A126695 |
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Numbers that can be expressed as the ratio between the product and the sum of n consecutive numbers with n>1. |
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+0
2
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| 1, 5, 8, 16, 20, 21, 33, 36, 40, 56, 65, 85, 96, 120, 133, 161, 176, 180, 208, 224, 225, 261, 280, 320, 341, 385, 408, 432, 456, 481, 533, 560, 616, 645, 705, 736, 756, 800, 833, 901, 936, 1008, 1045, 1120, 1121, 1152, 1160, 1232, 1240
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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Number = Product_{i=a..a+n-1} i / Sum_{i=a..a+n-1} i with a, n > 1
Integer values of (n+1)*binomial(a+n,a-1)/Sum_{i=0..n-1}(a+i) with a, n > 1
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EXAMPLE
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224 = 4*5*6*7*8/(4+5+6+7+8)
225 = 25*26*27/(25+26+27)
5544 = 11*12*13*14*15/(11+12+13+14+15)
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CROSSREFS
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Sequence in context: A039752 A141536 A065905 this_sequence A001082 A030006 A088586
Adjacent sequences: A126692 A126693 A126694 this_sequence A126696 A126697 A126698
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KEYWORD
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easy,nonn
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AUTHOR
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Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Feb 15 2007, corrected Feb 20 2007 and Mar 06 2007
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