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A108880 Alphabetically earliest number that is a product of exactly n primes. 0
8018018851, 8000000018, 8, 8018000018, 8018018886, 8018018085, 8018018808, 8000000008, 8018018000, 8018018048, 8018018816, 8018018176, 8018808000, 8018808832, 8018000000, 8018018304, 8018887680, 8018804736, 8018853888 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
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."
REFERENCES
Conway, J. H. and Guy, R. K. The Book of Numbers. New York: Springer-Verlag, p. 15, 1996.
LINKS
Eric Weisstein's World of Mathematics, Almost Prime.
EXAMPLE
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
CROSSREFS
Cf. A000052.
Sequence in context: A364436 A075131 A250865 * A204500 A290539 A017003
KEYWORD
nonn,word
AUTHOR
Jonathan Vos Post, Jul 14 2005
EXTENSIONS
Corrected and extended by Ray Chandler, Jul 25 2005
Definition clarified by N. J. A. Sloane, Sep 27 2011
STATUS
approved

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Last modified April 12 06:13 EDT 2024. Contains 371623 sequences. (Running on oeis4.)