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A359060
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Decimal expansion of Sum_{n >= 1} sigma_4(n)/n!.
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1
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4, 2, 3, 0, 1, 0, 4, 7, 5, 0, 3, 7, 3, 3, 5, 0, 8, 0, 6, 6, 8, 6, 4, 2, 8, 4, 0, 6, 2, 5, 3, 0, 7, 6, 4, 5, 3, 0, 5, 9, 5, 6, 7, 0, 6, 2, 2, 4, 9, 3, 3, 2, 3, 1, 5, 5, 1, 1, 8, 8, 7, 6, 9, 4, 9, 4, 2, 6, 8, 9, 9, 1, 3, 1, 9, 7, 6, 5, 8, 1, 2
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OFFSET
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2,1
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COMMENTS
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This constant's irrationality was conjectured by Erdős and Kac in 1953 and proved by Pratt in 2022.
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LINKS
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Paul Erdős and Mark Kac, Problem 4518, American Mathematical Monthly, Vol. 60, No. 1 (1953), p. 47.
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EXAMPLE
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42.301047503733508066864284062530764530595670622493323155118876949426899131....
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MATHEMATICA
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RealDigits[N[Sum[DivisorSigma[4, n]/n!, {n, 1, 500}], 120]][[1]] (* Amiram Eldar, Jun 21 2023 *)
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PROG
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(PARI) suminf(n=1, sigma(n, 4)/n!)
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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