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 A101261 a(2n-1) = 1; a(2n) = a(n)th smallest positive integer not among the earlier terms of the sequence. 2
 1, 2, 1, 4, 1, 3, 1, 8, 1, 5, 1, 9, 1, 6, 1, 16, 1, 7, 1, 14, 1, 10, 1, 21, 1, 11, 1, 19, 1, 12, 1, 32, 1, 13, 1, 24, 1, 15, 1, 34, 1, 17, 1, 30, 1, 18, 1, 45, 1, 20, 1, 36, 1, 22, 1, 47, 1, 23, 1, 40, 1, 25, 1, 64, 1, 26, 1, 44, 1, 27, 1, 59, 1, 28, 1, 51, 1, 29, 1, 74, 1, 31, 1, 56, 1, 33, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The sequence {a(2k)} forms a permutation of the integers >= 2. LINKS EXAMPLE a(12) = the a(6)th (the 3rd) smallest positive integer not among the first 11 terms of the sequence. Not among the first 11 terms are 6, 7, 9, 10,... The 3rd of these is 9, which is a(12). MATHEMATICA a[1] = 1; a[n_] := a[n] = If[ OddQ[n], 1, Complement[ Range[100], Union[ Table[ a[i], {i, n - 1}]]][[a[n/2]] ]]; Table[ a[n], {n, 90}] (* Robert G. Wilson v, Jan 13 2005 *) CROSSREFS Sequence in context: A256578 A127461 A329900 * A214057 A067614 A341308 Adjacent sequences:  A101258 A101259 A101260 * A101262 A101263 A101264 KEYWORD easy,nonn AUTHOR Leroy Quet, Dec 17 2004 EXTENSIONS More terms from Robert G. Wilson v, Jan 13 2005 STATUS approved

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Last modified May 9 08:50 EDT 2021. Contains 343699 sequences. (Running on oeis4.)