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Search: id:A108880
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| A108880 |
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Alphabetically first n-almost primes. |
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1
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| 8018018851, 8000000018, 8, 8018000018, 8018018886, 8018018085, 8018018808, 8000000008, 8018018000, 8018018048, 8018018816, 8018018176, 8018808000, 8018808832, 8018000000, 8018018304, 8018887680, 8018804736, 8018853888
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Conway and Guy note that 8018018851 is, alphabetically, the first prime number in the American system of large number terminology and term this "Knuth's number." We have "eight billion" alphabetically before "eighteen" or "eighty."
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REFERENCES
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Conway, J. H. and Guy, R. K. The Book of Numbers. New York: Springer-Verlag, p. 15, 1996.
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LINKS
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Eric Weisstein's World of Mathematics, Almost Prime.
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EXAMPLE
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n Alphabetically first n-almost prime
1 8018018851
2 8000000018 = 2 * 4000000009
3 8 = 2^3
4 8018000018 = 2 * 7 * 97 * 5904271
5 8018018886 = 2 * 3 * 19 * 6661 * 10559
6 8018018085 = 3 * 5 * 7 * 11 * 163 * 42589
7 8018018808 = 2^3 * 3 * 31 * 2161 * 4987
8 8000000008 = 2^3 * 7 * 11 * 13 * 19 * 52579
9 8018018000 = 2^4 * 5^3 * 127 * 31567
10 8018018048 = 2^8 * 43 * 728381
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CROSSREFS
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Cf. A000052.
Sequence in context: A095926 A015413 A075131 this_sequence A017003 A017075 A017267
Adjacent sequences: A108877 A108878 A108879 this_sequence A108881 A108882 A108883
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KEYWORD
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nonn,word
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Jul 14 2005
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EXTENSIONS
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Corrected and extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jul 25 2005
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