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A273978
List of words of length n over an alphabet of size 9 that are in standard order and which have the property that every letter that appears in the word is repeated.
2
11, 111, 1111, 1122, 1212, 1221, 11111, 11122, 11212, 11221, 11222, 12112, 12121, 12122, 12211, 12212, 12221, 111111, 111122, 111212, 111221, 111222, 112112
OFFSET
1,1
COMMENTS
We study words made of letters from an alphabet of size b, where b >= 1. (Here b=9.) We assume the letters are labeled {1,2,3,...,b}. There are b^n possible words of length n.
We say that a word is in "standard order" if it has the property that whenever a letter i appears, the letter i-1 has already appeared in the word. This implies that all words begin with the letter 1.
These are the words described in row b=9 of the array in A278987.
REFERENCES
D. D. Hromada, Integer-based nomenclature for the ecosystem of repetitive expressions in complete works of William Shakespeare, submitted to special issue of Argument and Computation on Rhetorical Figures in Computational Argument Studies, 2016.
LINKS
Daniel Devatman Hromada, Table of n, a(n) for n = 1..4360
Joerg Arndt and N. J. A. Sloane, Counting Words that are in "Standard Order"
PROG
#PERL checking whether numbers listed in A273977 and given in standard input belong to the current sequence
OUTER: while (<>) {
my %d;
$i=$_;
chop $i;
for $d (split //, $i) {
(exists $d{$d}) ? ($d{$d}++) : ($d{$d}=1);
}
for $k (keys %d) {
next OUTER if ($d{$k}<2);
}
print "$i\n";
}
CROSSREFS
Subset of A273977.
Cf. A278987.
Sequence in context: A114397 A336325 A098595 * A334131 A077488 A039988
KEYWORD
base,easy,nonn
AUTHOR
EXTENSIONS
Edited by N. J. A. Sloane, Dec 06 2016
STATUS
approved