A110898 a(n) = 1 + a(n - a(n-1)) - (n - a(n-1)) mod 3 + (n - a(n-2)) mod 4, with a(0) = 0, a(1) = 1.

0, 1, 3, 3, 2, 6, 1, 3, 8, 3, 5, 2, 8, 8, 4, 4, 9, 8, 6, 11, 6, 7, 5, 7, 10, 7, 11, 9, 12, 7, 8, 6, 10, 9, 7, 14, 6, 9, 6, 12, 14, 11, 6, 9, 15, 9, 12, 15, 10, 15, 13, 5, 17, 7, 15, 14, 8, 18, 16, 10, 12, 18, 16, 15, 15, 14, 20, 15, 6, 18, 17, 17, 17, 7, 16, 9, 15, 15, 19, 13, 16, 13, 21, 17

Offset

0,3

Links

G. C. Greubel, Table of n, a(n) for n = 0..10000

Mathematica

a[n_]:= a[n]= If[n<2, n, 1 +a[n-a[n-1]] +Mod[n-a[n-1], 3] -Mod[n-a[n-2], 3]];
Table[a[n], {n, 0, 100}]

Prog

(Magma) [n le 2 select n-1 else 1 + Self(n-Self(n-1)) - ((n+2-Self(n-1)) mod 3) + ((n+3-Self(n-2)) mod 4) : n in [1..101]]; // G. C. Greubel, Mar 30 2024
(SageMath)
@CachedFunction
def a(n): # a = A110898
    if n<2: return n
    else: return 1 +a(n-a(n-1)) -(n-a(n-1))%3 +(n-a(n-2))%4
[a(n) for n in range(101)] # G. C. Greubel, Mar 30 2024

Crossrefs

Cf. A110897.

Sequence in context: A329690 A293521 A285443 * A264756 A267942 A374481

Adjacent sequences: A110895 A110896 A110897 * A110899 A110900 A110901

Keyword

nonn,easy,less,changed

Author

Roger L. Bagula, Sep 20 2005

Extensions

Edited by G. C. Greubel, Mar 30 2024

Definition corrected by Georg Fischer, Jul 15 2026

Status

approved