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A094120
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a(n) = Sum_{k=1..n} Sum_{i=1..k} (-2)^valuation(i,2).
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1
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0, 1, 0, 0, 4, 9, 12, 16, 12, 9, 4, 0, 0, 1, 0, 0, 16, 33, 48, 64, 84, 105, 124, 144, 156, 169, 180, 192, 208, 225, 240, 256, 240, 225, 208, 192, 180, 169, 156, 144, 124, 105, 84, 64, 48, 33, 16, 0, 0, 1, 0, 0, 4, 9, 12, 16, 12, 9, 4, 0, 0, 1, 0, 0, 64, 129, 192, 256, 324, 393
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OFFSET
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0,5
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LINKS
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MATHEMATICA
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{0}~Join~Accumulate@ Accumulate@ Array[(-2)^IntegerExponent[#, 2] &, 69] (* Michael De Vlieger, Oct 30 2022 *)
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PROG
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(PARI) a(n)=sum(k=1, n, sum(i=1, k, (-2)^valuation(i, 2)))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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