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A225373 a(n) = 1 + Sum_{i=0..floor(n/2)} phi(n-2*i). 0
1, 2, 2, 4, 4, 8, 6, 14, 10, 20, 14, 30, 18, 42, 24, 50, 32, 66, 38, 84, 46, 96, 56, 118, 64, 138, 76, 156, 88, 184, 96, 214, 112, 234, 128, 258, 140, 294, 158, 318, 174, 358, 186, 400, 206, 424, 228, 470, 244, 512, 264, 544, 288, 596, 306, 636, 330, 672, 358, 730 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Number of Sturmian palindromes of length n.

LINKS

Table of n, a(n) for n=0..59.

Michelangelo Bucci, Alessandro De Luca, Amy Glen and Luca Q. Zamboni, A connection between palindromic and factor complexity using return words, arXiv:0802.1332 [math.CO], 2008.

FORMULA

a(n) = A106481(n) + 1. - Filip Zaludek, Dec 16 2016

MAPLE

with(numtheory);

f:=n->1+add(phi(n-2*i), i=0..floor(n/2));

[seq(f(n), n=0..100)];

MATHEMATICA

Table[1 + Sum[EulerPhi[n - 2 i], {i, 0, Floor[n/2]}], {n, 0, 59}] (* Michael De Vlieger, Dec 17 2016 *)

CROSSREFS

Cf. A000010.

Sequence in context: A175359 A008330 A191234 * A138219 A279405 A100835

Adjacent sequences:  A225370 A225371 A225372 * A225374 A225375 A225376

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, May 08 2013

EXTENSIONS

Name corrected by Michael De Vlieger, Dec 17 2016

STATUS

approved

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Last modified March 21 12:04 EDT 2019. Contains 321369 sequences. (Running on oeis4.)