OFFSET
1,1
EXAMPLE
3 and 40 are terms since 3 = thRee, and 40 = foRty.
MATHEMATICA
ok[n_] := Block[{s = StringReplace[IntegerName[n, "Words"], ", " | " " | "\[Hyphen]" -> ""], m}, m = StringLength[s]; OddQ[m] && (m = (m + 1)/2; StringTake[s, {m, m}] == "r")]; Select[ Range[5000], ok] (* Giovanni Resta, May 01 2017 *)
CROSSREFS
KEYWORD
nonn,word,less
AUTHOR
Claudio Meller, May 22 2009
EXTENSIONS
a(48)-a(51) from Giovanni Resta, May 01 2017
STATUS
approved