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Search: id:A073517
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| A073517 |
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Number of primes less than 10^n with initial digit 1. |
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+0
13
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| 0, 4, 25, 160, 1193, 9585, 80020, 686048, 6003530, 53378283, 480532488, 4369582734, 40063566855, 369893939287, 3435376839800, 32069022099022, 300694113015105, 2830466318006780, 26735673312004455, 253315661161665338
(list; graph; listen)
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OFFSET
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0,2
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LINKS
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Chris K. Caldwell, How Many Primes Are There?
Xavier Gourdan & Pascal Sebah, Counting the number of primes [sic]
Henri Lifchitz, Parity of Pi(n)
Thomas R. Nicely, Some Results of Computational Research in Prime Numbers
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EXAMPLE
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a(2)=4 because there are 4 primes up to 10^2 whose initial digit is 1 (11, 13, 17 and 19).
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MATHEMATICA
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f[n_] := f[n] = PrimePi[2*10^n] - PrimePi[10^n] + f[n - 1]; f[0] = 0; Table[ f[n], {n, 0, 13}]
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CROSSREFS
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Cf. A073509 to A073517, their sum is A006880.
Sequence in context: A091634 A010909 A079750 this_sequence A074422 A128419 A006880
Adjacent sequences: A073514 A073515 A073516 this_sequence A073518 A073519 A073520
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KEYWORD
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base,hard,nonn
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AUTHOR
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Shyam Sunder Gupta (guptass(AT)rediffmail.com), Aug 14 2002
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EXTENSIONS
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Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 29 2002
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