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Search: id:A086755
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| A086755 |
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Sum_{k=1..n} k(k+1)^2/2. |
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+0
1
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| 2, 20, 92, 292, 742, 1624, 3192, 5784, 9834, 15884, 24596, 36764, 53326, 75376, 104176, 141168, 187986, 246468, 318668, 406868, 513590, 641608, 793960, 973960, 1185210, 1431612, 1717380, 2047052, 2425502, 2857952, 3349984, 3907552
(list; graph; listen)
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OFFSET
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0,1
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FORMULA
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(n+1)(n+2)(n+3)(3n^2+12n+10)/30.
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EXAMPLE
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a(3)=(1*2)^2/2+(2*3)^2/2+(3.4)^2/2=2+18+72=92
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PROGRAM
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(PARI) for(i=1, 20, print1(", "sum(j=1, i, (j*(j+1))^2/2)))
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CROSSREFS
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Sequence in context: A071253 A069187 A033840 this_sequence A107483 A035599 A103101
Adjacent sequences: A086752 A086753 A086754 this_sequence A086756 A086757 A086758
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KEYWORD
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nonn,easy
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AUTHOR
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Jon Perry (perry(AT)globalnet.co.uk), Jul 31 2003
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EXTENSIONS
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More terms from Jason Earls (zevi_35711(AT)yahoo.com), Aug 01 2003
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