A283901 Relative of Hofstadter Q-sequence: a(-310) = 4, a(-309) = 311, a(-308) = 4, a(-307) = 311; thereafter a(n) = a(n-a(n-1)) + a(n-a(n-2)).

315, 4, 311, 315, 8, 315, 315, 622, 4, 315, 319, 622, 4, 315, 323, 622, 4, 315, 327, 622, 4, 315, 331, 622, 4, 315, 335, 622, 4, 315, 339, 622, 4, 315, 343, 622, 4, 315, 347, 622, 4, 315, 351, 622, 4, 315, 355, 622, 4, 315, 359, 622, 4

Offset

1,1

Comments

In calculating terms of this sequence, use the convention that a(n)=0 for n<=-311.

Sequences like this are more naturally considered with the first nonzero term in position 1. But this sequence would then begin with 311 terms consisting entirely of alternating 4's and 311's.

This sequence has exactly 658 terms, since a(658)=0 and computing a(659) would refer to itself.

a(n) = 2*a(n-4) - a(n-8) for 13 < n <= 312 and for 332 < n <= 623. - Chai Wah Wu, Jul 26 2020

Links

Nathan Fox, Table of n, a(n) for n = 1..658

Maple

A283901:=proc(n) option remember: if n <= -311 then 0: elif n = -310 then 4: elif n = -309 then 311: elif n = -308 then 4: elif n = -307 then 311: else A283901(n-A283901(n-1)) + A283901(n-A283901(n-2)): fi: end:

Crossrefs

Cf. A005185, A283898, A283899, A283900, A283902.

Sequence in context: A284078 A231021 A104819 * A207148 A361034 A210889

Adjacent sequences: A283898 A283899 A283900 * A283902 A283903 A283904

Keyword

nonn,fini,full

Author

Nathan Fox, Mar 19 2017

Status

approved