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%I #6 Apr 07 2020 03:39:58
%S 3,5,7,9,11,13,13,14,14,14,15,15,15,15,15,15,15,15,15,16,16,16,16,16,
%T 16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,
%U 16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16,16
%N Number of distinct letters needed to spell English names of numbers 1 through n.
%C Late increases are at twentY, hunDred, thousAnd, Million, Billion, Quadrillion, sePtillion, oCtillion.
%C Only J and K are never used for English number names. Z is used only for zero.
%e "One" has three letters, "two" brings two new letters (t w), "three" brings two more (h r)...
%Y Cf. A005589, A052360, A052362, A052363.
%K nonn,word,easy
%O 1,1
%A Peter F. Klammer (pklammer(AT)acm.org), May 17 2003
%E Edited by _Don Reble_, Nov 03 2003
%E More terms from _Jinyuan Wang_, Apr 07 2020