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Search: id:A164904
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A164904 a(n) is the number of palindromic structures of n-digit numbers. +0
1
1, 1, 1, 2, 2, 5, 5, 15, 15, 52, 52, 203, 203, 877, 877, 4140, 4140, 21147, 21147, 115975, 115975, 678569, 678569, 4213530, 4213530, 27641927, 27641927, 190829797, 190829797, 1381367941, 1381367941, 10448276360, 10448276360, 82285618467 (list; graph; listen)
OFFSET

0,4

COMMENT

a(n) is the number of palindromic word structures of length n using 10-ary alphabet. a(n) is the same as taking every element twice from A164864 - Number of ways of placing n labeled balls into 10 indistinguishable boxes; word structures of length n using a 10-ary alphabet.

EXAMPLE

Four-digit palindromes have two different digits structures: aaaa and abba. Hence a(4)=2.

CROSSREFS

A056471, A164864

Sequence in context: A055879 A056470 A056471 this_sequence A083849 A063501 A103892

Adjacent sequences: A164901 A164902 A164903 this_sequence A164905 A164906 A164907

KEYWORD

nonn,uned

AUTHOR

Tanya Khovanova (tanyakh(AT)yahoo.com), Aug 30 2009

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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