A087842 a(n) = a(a(a(n - a(n-1)))) + a(n - a(n-2)).

1, 1, 2, 3, 3, 3, 4, 4, 4, 4, 6, 5, 6, 6, 6, 6, 8, 7, 8, 8, 8, 8, 8, 8, 11, 9, 9, 11, 11, 11, 11, 11, 11, 11, 11, 14, 12, 11, 12, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 17, 15, 14, 14, 17, 17, 15, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 21, 18, 17, 17, 21, 20, 17, 21, 21, 21, 18, 21

Offset

1,3

Comments

A fourth-order recursive version of Hofstadter Q of the first term of A005185.

Links

Paolo P. Lava, Table of n, a(n) for n = 1..10000

Mathematica

digits=200 Hofstadter[n_Integer?Positive] := Hofstadter[n] = Hofstadter[Hofstadter[Hofstadter[n - Hofstadter[n-1]]]] + Hofstadter[n - Hofstadter[n-2]] Hofstadter[1] = Hofstadter[2] = 1 a1=Table[Hofstadter[n], {n, 1, digits}]

Crossrefs

Cf. A005185.

Sequence in context: A057627 A013940 A029129 * A201206 A101776 A189721

Adjacent sequences: A087839 A087840 A087841 * A087843 A087844 A087845

Keyword

nonn

Author

Roger L. Bagula, Oct 07 2003

Status

approved