A373230 Relative of Hofstadter Q-sequence: a(n) = 0 for n <= 0, a(n) = n for 1 <= n <= 10; a(n) = a(n-a(n-1)) + a(n-a(n-2)) + a(n-a(n-3)) for n > 10.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 6, 11, 12, 13, 9, 14, 15, 16, 12, 17, 18, 19, 15, 20, 21, 17, 23, 18, 23, 25, 26, 22, 21, 31, 29, 21, 28, 34, 27, 29, 31, 27, 38, 33, 34, 31, 39, 37, 37, 30, 44, 36, 39, 35, 43, 45, 43, 30, 50, 50, 38, 42, 51, 48, 43, 40, 55, 51, 52, 37, 60, 57, 47

Offset

1,2

Comments

Similar to A278055 but with different starting values.

a(1015) = 1036. This is the smallest index for which a(n) > n. So, without the condition that a(n) = 0 for n <= 0, this sequence would be finite and have exactly 1015 terms.

Much like the Hofstadter Q-sequence A005185, it is not known if this sequence is defined for all positive n.

a(n) exists for n <= 3*10^7.

Links

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

Mathematica

a[n_] := a[n] = Which[n < 1, 0, n < 11, n, True, a[n-a[n-1]] + a[n-a[n-2]] + a[n-a[n-3]]]; Array[a, 100] (* Paolo Xausa, May 31 2024 *)

Crossrefs

Cf. A005185, A278055, A373227, A373228, A373229, A373231, A373232, A373233.

Similar sequences based on the Q-recurrence: A278056, A278057, A278058, A278059, A278060, A278061, A278062, A278063, A278064, A278065.

Sequence in context: A305810 A171060 A254596 * A286603 A374485 A291751

Adjacent sequences: A373227 A373228 A373229 * A373231 A373232 A373233

Keyword

nonn

Author

Nathan Fox, May 28 2024

Status

approved