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A085864
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a(1) = 2, a(n+1) = a(n)*{tau(a(n))}.
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2
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2, 4, 12, 72, 864, 20736, 933120, 117573120, 42326323200, 36315985305600, 146426052752179200, 1475974611741966336000, 37784950060594338201600000, 2031318915257551621718016000000, 212719716805770805826310635520000000
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OFFSET
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1,1
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COMMENTS
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a(1) = 1, a(n+1) = a(n) + tau(a(n)) gives A064491.
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LINKS
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EXAMPLE
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a(4) = 72 and tau(72)= 12, hence a(5) = 72*12= 864.
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MATHEMATICA
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NestList[# DivisorSigma[0, #]&, 2, 20] (* Harvey P. Dale, Apr 23 2023 *)
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PROG
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(PARI) for(n=1, 16, if(n==1, a=2, a*=numdiv(a)); print(a); )
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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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