A114861 a(n) is smallest positive integer not among the earlier terms of the sequence, not equal to n and which is coprime to its adjacent terms in the sequence.
2, 1, 4, 3, 7, 5, 6, 11, 8, 9, 10, 13, 12, 17, 14, 15, 16, 19, 18, 23, 20, 21, 22, 25, 24, 29, 26, 27, 28, 31, 30, 37, 32, 33, 34, 35, 36, 41, 38, 39, 40, 43, 42, 47, 44, 45, 46, 49, 48, 53, 50, 51, 52, 55, 54, 59, 56, 57, 58, 61, 60, 67, 62, 63, 64, 65, 66, 71, 68, 69, 70, 73
Offset: 1
Keywords
Examples
a(8) = 11 since 11 is the smallest positive integer not among the first 7 terms of the sequence, not equal to 8 and which is coprime to a(7) = 6.
Crossrefs
Cf. A114862.
Programs
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Mathematica
f[l_] := Block[{k = 1}, While[k == Length[l] + 1 || MemberQ[l, k] || GCD[k, Last[l]] > 1, k++ ]; Return[Append[l, k]]; ]; Nest[f, {}, 76] (* Ray Chandler, Jan 02 2006 *)
Extensions
More terms from Ray Chandler and Klaus Brockhaus, Jan 02 2006
Comments