A283894 Relative of Hofstadter Q-sequence: a(1) = 17, a(2) = 2; thereafter a(n) = a(n-a(n-1)) + a(n-a(n-2)).

17, 2, 17, 2, 17, 2, 17, 2, 17, 2, 17, 2, 17, 2, 17, 2, 17, 19, 2, 36, 2, 36, 2, 36, 2, 36, 2, 36, 2, 36, 2, 36, 2, 36, 2, 36, 19, 4, 38, 38, 34, 4, 55, 38, 17, 4, 91, 38, 17, 4, 127, 38, 17, 21, 40, 4, 34, 57, 4, 21, 72, 34, 2, 70, 2, 70, 2, 70, 2, 70, 19, 19, 42, 76, 2

Offset

1,1

Comments

In calculating terms of this sequence, use the convention that a(n)=0 for n <= 0.

Most terms in this sequence alternate between 2 and a large number. Such runs of terms are separated by 102 other terms, and each run is approximately twice as long as the previous.

Links

Nathan Fox, Table of n, a(n) for n = 1..10000

Formula

For nonnegative integers i, if 1 <= 2n + r <= 594*2^(i+1) - 2, then

a(594*2^i + 100 + 2n) = 2

a(594*2^i + 100 + 2n + 1) = 594*2^(i+1) - 2.

Maple

A283894:=proc(n) option remember: if n <= 0 then 0: elif n = 1 then 17: elif n = 2 then 2: else A283894(n-A283894(n-1)) + A283894(n-A283894(n-2)): fi: end:

Crossrefs

Cf. A005185, A278066, A278067, A278068, A283893, A283895, A283896, A283897.

Sequence in context: A051311 A040287 A252940 * A016735 A034059 A303733

Adjacent sequences: A283891 A283892 A283893 * A283895 A283896 A283897

Keyword

nonn

Author

Nathan Fox, Mar 19 2017

Status

approved