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 A239350 Superprimorials squared. 3
 1, 4, 144, 129600, 5715360000, 30497732496000000, 27502882612852046400000000, 7167813920637790505994548640000000000, 674376505248717910810215697948155164304000000000000, 33564007734235791949707248640534383334045138980782017600000000000000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Square of product of first n primorials = A006939(n)^2. Smallest number with n distinct even exponents in its prime factorization. The prime version of Ramanujan's infinite nested radical 1*sqrt(1+2*sqrt(1+3*sqrt(1+…)))) is 2*sqrt(1+3*sqrt(1+5*sqrt(1+…))) = sqrt(4+sqrt(144+sqrt(129600+…))) = sqrt(a(1)+sqrt(a(2)+sqrt(a(3)+…))). See A239349 and A055209. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..27 FORMULA a(n) = Product_{k=1..n} A002110(k)^2 = Product_{k=1..n} prime(k)^(2(n-k+1)). MATHEMATICA Rest[FoldList[Times, 1, FoldList[Times, 1, Prime[Range[9]]^2]]] CROSSREFS Cf. A002110, A055209, A006939, A239349. Sequence in context: A138176 A203424 A055209 * A343697 A030450 A041629 Adjacent sequences: A239347 A239348 A239349 * A239351 A239352 A239353 KEYWORD nonn AUTHOR Jonathan Sondow, Mar 22 2014 STATUS approved

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Last modified June 12 10:35 EDT 2024. Contains 373331 sequences. (Running on oeis4.)