A267501 Relative of Hofstadter Q-sequence: a(n) = 0 if n <= 0, a(1) = a(2) = a(3) = 1; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 3.

1, 1, 1, 3, 7, 8, 3, 8, 10, 4, 5, 12, 19, 11, 4, 19, 27, 11, 8, 22, 23, 11, 13, 25, 23, 21, 12, 29, 35, 12, 9, 35, 48, 23, 12, 44, 34, 24, 11, 62, 39, 10, 51, 30, 16, 31, 55, 62, 11, 11, 124, 78, 10, 30, 39, 79, 23, 20, 55, 103, 47, 7, 98

Offset

1,4

Comments

This sequence has exactly 416 terms. a(416) = 0, so an attempt to calculate a(417) would refer to itself.

Without the convention that a(n) = 0 for n <= 0, this sequence would have exactly five terms, since computing a(6) refers to a(-1).

Links

Nathan Fox, Table of n, a(n) for n = 1..416 (full sequence)

Example

a(10) = 4 because a(9) is 10, a(8) is 8, and a(7) is 3, so we take a(10 - 10) + a(10 - 8) + a(10 - 3) = a(0) + a(2) + a(7) = 0 + 1 + 3 = 4.

Crossrefs

Cf. A005185

Sequence in context: A078004 A197728 A340315 * A016667 A006834 A309419

Adjacent sequences: A267498 A267499 A267500 * A267502 A267503 A267504

Keyword

nonn,fini,full

Author

Nathan Fox, Feb 23 2016

Status

approved