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Search: id:A049413
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| A049413 |
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Highest prime dividing sum{k=0 to n}[ k!(n-k)! ]. |
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+0
1
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| 2, 5, 2, 2, 13, 151, 3, 83, 73, 1433, 647, 29, 28211, 337, 19, 73, 18181, 130349, 771079, 731957, 6619, 4111, 61927, 140001721, 42829, 774885169, 745984697, 41711914513, 34311919, 117695654963, 1139908799, 2390249, 54413
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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sum{k=0 to n}[ k!(n-k)! ]=(n+1)!sum{k=0 to n}[ 1/((k+1)2^(n-k)) ]
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EXAMPLE
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a(5)=13 because sum{k=0 to 5}[ k!(5-k)! ]=312=2^3*3*13.
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MAPLE
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for n from 1 to 33 do s := 0:for k from 0 to n do s := s+k!*(n-k)!:od:ifactor(s); od;
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CROSSREFS
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Sequence in context: A065291 A065267 A100955 this_sequence A102720 A102707 A134486
Adjacent sequences: A049410 A049411 A049412 this_sequence A049414 A049415 A049416
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KEYWORD
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nonn,easy
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com)
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EXTENSIONS
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More terms from Andrew Gacek (andrew(AT)dgi.net), Apr 21 2000
Corrected by Jud McCranie (j.mccranie(AT)comcast.net), Jan 03 2001
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