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1, 3, 17, 41, 125, 321, 745, 1777, 4089, 9217, 20417, 45009, 98273, 212977, 458753, 982881, 2097025, 4456353, 9437121, 19922913, 41943041, 88080001, 184549057, 385875713, 805306177, 1677721473, 3489660865, 7247757313, 15032384641, 31138512129, 64424508801
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OFFSET
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1,2
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COMMENTS
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At one time this expression was proposed (erroneously) as a formula for A007664.
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LINKS
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MATHEMATICA
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f[n_] := Floor[Sqrt[2*n] + 1/2]; a[n_] := Sum[ i*2^(i - 1), {i, 1, n}] - (f[n]*(f[n] + 1)/2 - n)*2^(f[n] - 1); Table[a[n], {n, 1, 25}] (* G. C. Greubel, Oct 14 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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STATUS
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approved
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