A268182 A solution to a(n+1) in {a(n)+2, a(n)-2, a(n)*2, a(n)/2} which is a rearrangement of the natural numbers.
2, 1, 3, 6, 4, 8, 10, 5, 7, 9, 11, 22, 20, 18, 16, 14, 12, 24, 26, 13, 15, 17, 19, 21, 23, 25, 27, 54, 52, 50, 48, 46, 44, 42, 40, 38, 36, 34, 32, 30, 28, 56, 58, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59
Offset: 1
Keywords
Crossrefs
Cf. A168616.
Programs
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PARI
{get_next_stage(v) = local(k = (v[#v] - 1)/2); forstep(m = 2*v[#v], 2*k + 2, -2, v = concat(v, m)); v = concat(v, [2*v[#v], 4*k + 6]); forstep(m = v[#v]/2, 4*k + 7, 2, v = concat(v, m)); v} a = [2, 1, 3]; \\ code assumes last entry here is odd. \\ n-th call to function returns 2^(n + 2) more terms while (#a < 59, a = get_next_stage(a)); a \\ Rick L. Shepherd, May 21 2016
Formula
a(n) = n if and only if n is a positive term of A168616. Also, for j > 2, a(n) < a(2^j - 5) if and only if n < 2^j - 5. - Rick L. Shepherd, May 22 2016
Comments