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A007058 Let S denote the palindromes in the language {0,1,2,3,4}*; a(n) = number of words of length n in the language SS.
(Formerly M3936)
3
1, 5, 25, 65, 265, 605, 2125, 4345, 14665, 27965, 93025, 171825, 559645, 1015565, 3276725, 5857865, 18734665, 33203045, 105436225, 185546785, 585842065, 1025381485, 3222484125, 5615234265, 17577530845, 30517575605, 95213827825, 164794865465, 512692025285, 885009765485, 2746575977125 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=0..30.

R. Kemp, On the number of words in the language {w in Sigma* | w = w^R }^2, Discrete Math., 40 (1982), 225-234.

FORMULA

a(n) = A187275(n) - Sum_{d|n,d<n} phi(n/d)*a(d). - Sean A. Irvine, Sep 27 2017

MAPLE

See A007055.

CROSSREFS

Column 5 of A284873.

Cf. A007055, A007056, A007057.

Sequence in context: A179131 A054994 A108403 * A071383 A088959 A018782

Adjacent sequences:  A007055 A007056 A007057 * A007059 A007060 A007061

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Mira Bernstein, R. Kemp

EXTENSIONS

Entry revised by N. J. A. Sloane, Mar 07 2011

STATUS

approved

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Last modified May 26 19:20 EDT 2019. Contains 323597 sequences. (Running on oeis4.)