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A225373
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a(n) = 1 + Sum_{i=0..floor(n/2)} phi(n-2*i).
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0
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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
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OFFSET
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0,2
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COMMENTS
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Number of Sturmian palindromes of length n.
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LINKS
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FORMULA
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MAPLE
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with(numtheory);
f:=n->1+add(phi(n-2*i), i=0..floor(n/2));
[seq(f(n), n=0..100)];
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MATHEMATICA
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Table[1 + Sum[EulerPhi[n - 2 i], {i, 0, Floor[n/2]}], {n, 0, 59}] (* Michael De Vlieger, Dec 17 2016 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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