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A106481
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An Euler phi transform of 1/(1 - x^2).
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2
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0, 1, 1, 3, 3, 7, 5, 13, 9, 19, 13, 29, 17, 41, 23, 49, 31, 65, 37, 83, 45, 95, 55, 117, 63, 137, 75, 155, 87, 183, 95, 213, 111, 233, 127, 257, 139, 293, 157, 317, 173, 357, 185, 399, 205, 423, 227, 469, 243, 511, 263, 543, 287, 595, 305, 635, 329, 671, 357, 729
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listen;
history;
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OFFSET
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0,4
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LINKS
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FORMULA
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a(n) = Sum_{k=0..n} phi(n-k+1)*(k mod 2).
Euler transform of period 7 sequence [3,-2,-1,-1,-2,3,0,...].
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PROG
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(PARI) a(n) = sum(k=0, n, if (k%2, eulerphi(n-k+1))); \\ Michel Marcus, Jun 12 2024
(Python)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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