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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 Table of n, a(n) for n=1..19. 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 Adjacent sequences: A108877 A108878 A108879 * A108881 A108882 A108883 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.)