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A087234 Smallest deficient number with n distinct prime factors. 0
2, 10, 105, 1155, 36465, 969969, 37182145, 1078282205, 39896441585, 2668861960765, 183330286997165, 14415008697720995, 775932344695001065 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(14) <= 45780008337005062835. a(15) <= 3909612711980232366109. a(16) <= 261944051702675568529303. [From Donovan Johnson, Jan 25 2009]

LINKS

Table of n, a(n) for n=1..13.

FORMULA

a(n)=Min{x; sigma[x]/2x < 1 and A001221(x)=n}

EXAMPLE

n=5: a(n)=36465=3.5.11.13.17; sigma[36465]=72576<72930=2.sigma[a(n)].

MATHEMATICA

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}]

CROSSREFS

Cf. A000203, A002110, A005100.

Sequence in context: A005799 A208730 A000595 * A273965 A273961 A049538

Adjacent sequences:  A087231 A087232 A087233 * A087235 A087236 A087237

KEYWORD

nonn,more

AUTHOR

Labos Elemer, Sep 01 2003

EXTENSIONS

a(6) corrected and a(7)-a(13) from Donovan Johnson, Jan 25 2009

STATUS

approved

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Last modified June 23 09:32 EDT 2018. Contains 305693 sequences. (Running on oeis4.)