A345886 a(1) = 1, a(n) = a(n-1)/3 if a(n-1) is divisible by 3, otherwise a(n) = n - a(n-1).
1, 1, 2, 2, 3, 1, 6, 2, 7, 3, 1, 11, 2, 12, 4, 12, 4, 14, 5, 15, 5, 17, 6, 2, 23, 3, 1, 27, 9, 3, 1, 31, 2, 32, 3, 1, 36, 12, 4, 36, 12, 4, 39, 13, 32, 14, 33, 11, 38, 12, 4, 48, 16, 38, 17, 39, 13, 45, 15, 5, 56, 6, 2, 62, 3, 1, 66, 22, 47, 23, 48, 16, 57, 19, 56, 20, 57, 19, 60, 20, 61, 21, 7, 77, 8
Offset: 1
Crossrefs
Cf. A345877.
Programs
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Mathematica
a[1] = 1; a[n_] := a[n] = If[Divisible[a[n - 1], 3], a[n - 1]/3, n - a[n - 1]]; Array[a, 100] (* Amiram Eldar, Jun 29 2021 *)
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PARI
q=vector(100); q[1]=1; for(n=2, #q, q[n] = if(q[n-1]%3, n-q[n-1], q[n-1]/3)); q
Comments