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 A130420 a(n) = n-th positive integer which is coprime to n!!, where n!! = n*(n-2)*(n-4)..*(2 or 1). 1
 1, 3, 4, 7, 8, 17, 16, 23, 19, 37, 29, 43, 37, 59, 41, 67, 53, 73, 62, 83, 67, 101, 79, 107, 83, 127, 89, 137, 103, 149, 113, 157, 122, 173, 128, 181, 139, 197, 146, 211, 158, 227, 173, 233, 179, 251, 194, 263, 199, 271, 206, 281, 223, 293, 227, 311, 233, 331, 251 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE 3!! = 3; the first number coprime to 3 is 1, the second one is 2, the third one is 4. Thus a(3) = 4. MATHEMATICA a[n_] := Module[{in}, in = 0; k = 0; While[in != n, k++; If[GCD[n!!, k] == 1, in++ ]]; k]; Table[a[i], {i, 1, 80}] (* Stefan Steinerberger, May 30 2007 *) CROSSREFS Cf. A130419, A119992. Sequence in context: A306612 A117587 A244930 * A214096 A169943 A215110 Adjacent sequences:  A130417 A130418 A130419 * A130421 A130422 A130423 KEYWORD less,nonn AUTHOR Leroy Quet, May 25 2007 EXTENSIONS More terms from Stefan Steinerberger, May 30 2007 STATUS approved

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Last modified September 28 19:16 EDT 2021. Contains 347717 sequences. (Running on oeis4.)