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Search: id:A087234
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| A087234 |
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Smallest deficient number with n distinct prime factors. |
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+0
1
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| 2, 10, 105, 1155, 36465, 969969, 37182145, 1078282205, 39896441585, 2668861960765, 183330286997165, 14415008697720995, 775932344695001065
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(14) <= 45780008337005062835. a(15) <= 3909612711980232366109. a(16) <= 261944051702675568529303. [From Donovan Johnson (donovan.johnson(AT)yahoo.com), Jan 25 2009]
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FORMULA
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a(n)=Min{x; sigma[x]/2x < 1 and A001221(x)=n}
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EXAMPLE
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n=5: a(n)=36465=3.5.11.13.17; sigma[36465]=72576<72930=2.sigma[a(n)].
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MATHEMATICA
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q[x_] := Apply[Times, Table[Prime[w], {w, 1, x}]]; q[0]=1; Do[s=DivisorSigma[1, n]; If[Greater[2*n, s]&&Equal[lf[n], j]&& Equal[fl, 1], Print[{n, {s, 2*n}, j}]; fl=0], {n, q[j], q[j+2]}], {j, 1, 6}]
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CROSSREFS
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Cf. A000203, A002110, A005100.
Sequence in context: A154256 A005799 A000595 this_sequence A049538 A127728 A003222
Adjacent sequences: A087231 A087232 A087233 this_sequence A087235 A087236 A087237
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KEYWORD
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nonn,more
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Sep 01 2003
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EXTENSIONS
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a(6) corrected and a(7)-a(13) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jan 25 2009
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