A103154 Each letter appears an even number of times in the English names for 1 through n taken together (names without "and").

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

Robert Israel, Table of n, a(n) for n = 1..10000

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

Adjacent sequences: A103151 A103152 A103153 * A103155 A103156 A103157

Keyword

nonn,word

Author

David W. Wilson, Jan 24 2005

Status

approved