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Search: id:A115644
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| A115644 |
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Brilliant numbers (A078972) that are sums of distinct factorials. |
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+0
3
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| 6, 9, 25, 121, 841, 871, 5041, 5767, 363721, 368761, 409111, 3633841, 3992431, 3992551, 4032121, 4037791, 39962281, 39962311, 39963031, 40279711, 40279801, 43585921, 43591687, 43909207, 479047801, 479365321, 479370271, 482631271
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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39962281 = 11! + 8! + 7! + 5!+ 1! = 4861*8221.
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MATHEMATICA
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brillQ[n_] := Block[{d = FactorInteger[n]}, Plus@@Last/@d==2 && (Last/@d=={2} || Length@IntegerDigits@((First/@d)[[1]])==Length@IntegerDigits@((First/@d)[[2]]))]; fac=Range[20]!; lst={}; Do[ n = Plus@@(fac*IntegerDigits[k, 2, 20]); If[brillQ[n], AppendTo[lst, n]], {k, 2^20-1}]; lst
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CROSSREFS
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Cf. A078972, A025494, A115645, A115646, A089359.
Sequence in context: A084431 A093153 A115646 this_sequence A024878 A007414 A025493
Adjacent sequences: A115641 A115642 A115643 this_sequence A115645 A115646 A115647
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KEYWORD
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nonn
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AUTHOR
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Giovanni Resta (g.resta(AT)iit.cnr.it), Jan 27 2006
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