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 A097250 Smallest m such that A097249(m) = n; from n=1 onwards, twice the primorials, 2*A002110(n). 6
 1, 4, 12, 60, 420, 4620, 60060, 1021020, 19399380, 446185740, 12939386460, 401120980260, 14841476269620, 608500527054420, 26165522663340060, 1229779565176982820, 65178316954380089460, 3845520700308425278140, 234576762718813941966540, 15716643102160534111758180 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS A097249(a(n))=n and A097249(m)=1. - G. C. Greubel, Apr 23 2017 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 FORMULA a(n) = if n=0 then 1 else 2*A002110(n). MATHEMATICA Join[{1}, 2 Denominator[Accumulate[1/Prime[Range[20]]]]] (* Vincenzo Librandi, Mar 25 2017 *) Join[{1}, 2*FoldList[Times, 1, Prime[Range[50]]]] (* G. C. Greubel, Apr 23 2017 *) CROSSREFS Cf. A002110, A088860, A097249. From a(1)=4 onwards, row 3 of A276945. Sequence in context: A276707 A083484 A088860 * A188328 A291772 A222645 Adjacent sequences:  A097247 A097248 A097249 * A097251 A097252 A097253 KEYWORD nonn AUTHOR Reinhard Zumkeller, Aug 03 2004 EXTENSIONS Name amended by Antti Karttunen, Sep 24 2016 a(18)-a(19) from Vincenzo Librandi, Mar 25 2017 STATUS approved

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Last modified November 27 05:27 EST 2020. Contains 338678 sequences. (Running on oeis4.)