A087817 a(n) = a(a(a(n-1)))+a(n-a(n-1)).

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

Offset: 0

Author

Roger L. Bagula, Oct 05 2003

Keywords

• nonn

Links

• Michel Marcus, Table of n, a(n) for n = 0..999

Crossrefs

Cf. A004001. Different from A087836.

Programs

Mathematica

a[1] = a[2] = 1; a[n_Integer?Positive] :=a[n] = a[a[a[n - 1]]] + a[n - a[n - 1]]; Table[a[n], {n, 1, digits}]

PARI

lista(nn) = {va = vector(nn); va[1] = 1; va[2] = 1; for (n=3, nn, va[n] = va[va[va[n-1]]]+va[n-va[n-1]];); va;} \\ Michel Marcus, Aug 06 2017

Formula

Conjecture: a(n) is asymptotic to n^c with c=0.677.... - Benoit Cloitre, Jun 05 2004