

A073418


Useless numbers: numbers written in English without any of the letters e, s or u.


0



2, 30, 32, 40, 42, 50, 52, 2000000, 2000002, 2000030, 2000032, 2000040, 2000042, 2000050, 2000052, 30000000, 30000002, 30000030, 30000032, 30000040, 30000042, 30000050, 30000052, 32000000, 32000002, 32000030, 32000032, 32000040, 32000042, 32000050, 32000052
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OFFSET

1,1


COMMENTS

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


LINKS

Table of n, a(n) for n=1..31.
M. J. Halm, Sequences (Re)discovered, Mpossibilities 81 (Aug. 2002).
Eric Weisstein's World of Mathematics, Large Number
Wikipedia, Names of Large Numbers


EXAMPLE

a(2) = 30 because 30 is the second integer without an e, s or u in its English name.


CROSSREFS

Sequence in context: A228937 A071056 A075716 * A022377 A145290 A343930
Adjacent sequences: A073415 A073416 A073417 * A073419 A073420 A073421


KEYWORD

nonn,word


AUTHOR

Michael Joseph Halm, Aug 23 2002


EXTENSIONS

Removed 'ninety' and 'ninety two' from the sequence which clearly include the letter E. Likewise removed 'two hundrEd' and others. Inserted 'thirty' and 'thirtytwo'.  Freddie Noble, Jan 01 2021
a(16)a(31) from Michael S. Branicky, Jan 01 2021


STATUS

approved



