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 A075824 Odd numbers that cannot be expressed as 2^n-3^m where n and m are integers. 2
 9, 11, 17, 19, 21, 25, 27, 33, 35, 39, 41, 43, 45, 49, 51, 53, 57, 59, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 103, 105, 107, 109, 111, 113, 115, 117, 121, 123, 129, 131, 133, 135, 137, 139, 141, 143, 145, 147, 149, 151, 153, 155, 157 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All listed terms can be certified by considering 2^n-3^m modulo 2552550. [Max Alekseyev, Feb 08 2010] REFERENCES R. K. Guy, Unsolved Problems in Number Theory, D9. T. N. Shorey and R. Tijdeman, Exponential Diophantine Equations, Cambridge University Press, 1986. LINKS T. Metsankyla, Catalan's Conjecture : Another old Diophantine problem solved, Bull. Amer. Math. Soc. 41 (2004), 43-57. Wikipedia, Catalan's conjecture EXAMPLE 5 doesn't belong to the sequence because it can be expressed as 2^3-3^1. CROSSREFS Cf. A074981, A192110, A328077. Sequence in context: A216976 A236390 A048464 * A228951 A108113 A111391 Adjacent sequences:  A075821 A075822 A075823 * A075825 A075826 A075827 KEYWORD nonn AUTHOR Felice Russo, Oct 14 2002 EXTENSIONS Inserted "odd" in definition. - N. J. A. Sloane, Jan 30 2009 Jon E. Schoenfield observed that 49 was missing, Jan 30 2009 More terms from Max Alekseyev, Feb 08 2010 STATUS approved

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Last modified January 23 07:07 EST 2020. Contains 331168 sequences. (Running on oeis4.)