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A103154
Each letter appears an even number of times in the English names for 1 through n taken together (names without "and").
3
119, 139, 159, 179, 199, 319, 339, 359, 379, 399, 519, 539, 559, 579, 599, 719, 739, 759, 779, 799, 919, 939, 959, 979, 999, 1119, 1139, 1159, 1179, 1199, 1319, 1339, 1359, 1379, 1399, 1519, 1539, 1559, 1579, 1599, 1719, 1739, 1759, 1779, 1799, 1919
OFFSET
1,1
LINKS
FORMULA
It appears that a(n+5)=a(n)+200. - Robert Israel, Mar 17 2020
EXAMPLE
Together the English words for 1 through 119 contain 40 d's, 218 e's, 56 f's, 22 g's, 64 h's, 100 i's, 4 l's, 144 n's, 62 o's, 64 r's, 44 s's, 150 t's, 32 u's, 36 v's, 22 w's, 22 x's and 80 y's. All counts are even so 119 is in the sequence.
MAPLE
letters:= [$"a".."z"]:
V:= Vector(26):
Res:= NULL: count:= 0:
for n from 1 while count < 100 do
S:= convert(n, english);
V:= V + <seq(StringTools:-CountCharacterOccurrences(S, letters[i]), i=1..26)>;
if andmap(type, V, even) then
count:= count+1; Res:= Res, n;
fi
od:
Res; # Robert Israel, Mar 17 2020
CROSSREFS
Sequence in context: A133626 A124074 A231372 * A039557 A095629 A046007
KEYWORD
nonn,word
AUTHOR
David W. Wilson, Jan 24 2005
STATUS
approved