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%I #24 Jan 02 2021 04:25:21
%S 2,30,32,40,42,50,52,2000000,2000002,2000030,2000032,2000040,2000042,
%T 2000050,2000052,30000000,30000002,30000030,30000032,30000040,
%U 30000042,30000050,30000052,32000000,32000002,32000030,32000032,32000040,32000042,32000050,32000052
%N Useless numbers: numbers written in English without any of the letters e, s or u.
%C After a(7), the sequence contains only terms of the form a(i) * 10^(3*k) and a(i) * 10^(3*k) + a(j) for 1 <= i, j <= 7, where the name of 10^(3*k) is useless, e.g., 10^6 (million), 10^9 (billion), 10^12 (trillion), 10^27 (octillion), 10^30 (nonillion), ... (see links for large number names). - _Michael S. Branicky_, Jan 01 2021
%H M. J. Halm, <a href="https://michaelhalm.tripod.com/id109.htm">Sequences (Re)discovered</a>, Mpossibilities 81 (Aug. 2002).
%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LargeNumber.html">Large Number</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Names_of_large_numbers">Names of Large Numbers</a>
%e a(2) = 30 because 30 is the second integer without an e, s or u in its English name.
%K nonn,word
%O 1,1
%A _Michael Joseph Halm_, Aug 23 2002
%E Removed 'ninety' and 'ninety two' from the sequence which clearly include the letter E. Likewise removed 'two hundrEd' and others. Inserted 'thirty' and 'thirty-two'. - _Freddie Noble_, Jan 01 2021
%E a(16)-a(31) from _Michael S. Branicky_, Jan 01 2021