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Search: id:A110376
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| A110376 |
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SUM (n!/r) where r is relatively prime to n and less than n. |
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+0
3
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| 1, 2, 9, 32, 250, 864, 12348, 67584, 804816, 5760000, 116915040, 686776320, 19323757440, 157991178240, 2951575200000, 42301705420800, 1202482800691200, 10048607738265600, 425162773111910400, 4541227794432000000
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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a(6) = 6!{1/1 +1/5}=864.
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MAPLE
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a:=proc(n) local s, r: s:=0: for r from 1 to n do if gcd(r, n)=1 then s:=s+1/r else s:=s: fi: od: n!*s end: seq(a(n), n=1..23); (Deutsch)
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MATHEMATICA
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Do[Print[n! * Plus @@ Map[(1/#)&, Select[Range[n], GCD[ #, n] == 1 &]]], {n, 1, 30}] (Propper)
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CROSSREFS
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Cf. A110373, A110374, A038048.
Sequence in context: A150920 A013501 A114853 this_sequence A036505 A056916 A139628
Adjacent sequences: A110373 A110374 A110375 this_sequence A110377 A110378 A110379
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KEYWORD
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easy,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jul 24 2005
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Ryan Propper (rpropper(AT)stanford.edu) and Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jul 25 2005
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