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A045526
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Numbers k such that k! has initial digit '7'.
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18
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6, 56, 80, 156, 161, 170, 186, 200, 230, 238, 277, 288, 305, 307, 323, 325, 327, 344, 385, 410, 451, 454, 472, 475, 504, 532, 547, 551, 575, 592, 601, 615, 645, 661, 697, 710, 724, 731, 790, 800, 811, 822, 848
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OFFSET
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1,1
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COMMENTS
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The asymptotic density of this sequence is log_10(8/7) = 0.057991... (Kunoff, 1987). - Amiram Eldar, Jul 17 2020
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LINKS
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FORMULA
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EXAMPLE
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6 is a term since 6! = 720 has the initial digit 7.
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MATHEMATICA
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Select[ Range[ 900 ], IntegerDigits[ #! ] [[1]] == 7 & ]
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PROG
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(PARI) isok(n) = digits(n!)[1] == 7; \\ Michel Marcus, Feb 08 2017
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CROSSREFS
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For factorials with initial digit d (1 <= d <= 9) see A045509, A045510, A045511, A045516, A045517, A045518, A282021, A045519; A045520, A045521, A045522, A045523, A045524, A045525, A045526, A045527, A045528, A045529. See also A000142, A008905.
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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