A050074 a(n) = |a(n-1) - a(m)| for n >= 4, where m = 2^(p+1) + 2 - n and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1, a(2) = 2, and a(3) = 3.

1, 2, 3, 1, 0, 1, 2, 0, 1, 1, 1, 0, 0, 1, 2, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 1, 2, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 1, 2, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0

Offset

1,2

Links

Table of n, a(n) for n=1..90.

Maple

a := proc(n) option remember;
`if`(n < 4, [1, 2, 3][n], abs(a(n - 1) - a(Bits:-Iff(n - 2$2) + 3 - n)))
     end:
seq(a(n), n = 1..90); # Petros Hadjicostas, Nov 08 2019

Prog

(PARI) lista(nn) = {nn = max(nn, 3); my(va = vector(nn)); va[1] = 1; va[2] = 2; va[3] = 3; for(n=4, nn, va[n] = abs(va[n-1] - va[2 - n + 2*2^logint(n-2, 2)])); va; } \\ Petros Hadjicostas, May 15 2020

Crossrefs

Sequence in context: A004566 A321896 A321897 * A346688 A278313 A006705

Adjacent sequences: A050071 A050072 A050073 * A050075 A050076 A050077

Keyword

nonn

Author

Clark Kimberling

Extensions

Name edited by Petros Hadjicostas, Nov 08 2019

Status

approved