A283426 a(1) = a(2) = a(3) = a(4) = 1; a(n) = a(n-a(n-2)-1) + a(n-a(n-4)-2) for n > 4.

1, 1, 1, 1, 2, 2, 2, 4, 4, 4, 4, 4, 6, 8, 8, 6, 8, 8, 8, 8, 8, 10, 14, 14, 12, 12, 12, 12, 14, 14, 14, 16, 16, 16, 16, 16, 16, 16, 18, 24, 24, 22, 22, 16, 18, 24, 26, 28, 24, 22, 26, 24, 24, 28, 26, 26, 28, 26, 28, 32, 30, 30, 32, 30, 32, 32, 32, 32, 32, 32, 32, 34, 42, 42

Offset: 1

Author

Altug Alkan, May 15 2017

Keywords

• nonn
• look

Comments

For n < 10^5, values of a(n) such that a(n) = a(n + k) for all k = 1..6 are 2^4, 2^5, .., 2^14, 2^15.

Links

• Altug Alkan, Table of n, a(n) for n = 1..10000
• Altug Alkan, Line graph of A283426

Crossrefs

Cf. A005185, A240809.

Programs

Mathematica

a[1] = a[2] = a[3] = a[4] = 1; a[n_] := a[n] = a[n - a[n - 2] - 1] + a[n - a[n - 4] - 2]; Array[a, 74] (* Michael De Vlieger, May 15 2017 *)

PARI

q=vector(10000); q[1]=q[2]=q[3]=q[4]=1; for(n=5, #q, q[n]=q[n-1-q[n-2]]+q[n-2-q[n-4]]); vector(10000, n, q[n])