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A138113
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a(n) is the smallest number with same number of divisors as n*a(n-1).
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3
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1, 2, 6, 24, 120, 720, 5040, 27720, 166320, 1441440, 7207200, 73513440, 367567200, 4655851200, 64250746560, 1028011944960, 5140059724800, 32607253879200, 260858031033600, 4620913692595200, 97039187544499200, 897612484786617600, 9873737332652793600
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OFFSET
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1,2
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LINKS
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FORMULA
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EXAMPLE
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For n=8, n*a(n-1) = 8*5040 = 40320 has 96 divisors, but the smallest number with 96 divisors is 27720, so a(8)=27720.
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PROG
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(PARI) A138113(n)={ local(an1, t) ; if(n<=2, return(n) ) ; an1 = A138113(n-1) ; t=length(divisors(n*an1)) ; return(A005179(t)) ; } {for (n=1, 40, print1(A138113(n)", ") ; ) } \\ R. J. Mathar, Mar 20 2010
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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