A071898 CONTINUANT transform of A002487: 1, 1, 2, 1, 3, 2, ...

1, 2, 5, 7, 26, 59, 203, 262, 1251, 4015, 21326, 46667, 254661, 810650, 3497261, 4307911, 25036816, 104455175, 756223041, 2373124298, 19741217425, 101079211423, 727295697386, 1555670606195, 11616989940751, 59640620309950, 488741952420351, 1525866477571003

Offset: 1

Author

N. J. A. Sloane, Jun 10 2002

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..400
• N. J. A. Sloane, Transforms

Crossrefs

Cf. A002487.

Programs

Maple

b:= proc(n) option remember; `if`(n<2, n,
      `if`(irem(n, 2, 'r')=0, b(r), b(r) + b(r+1)))
    end:
a:= proc(n) option remember; `if`(n<0, 0,
      `if`(n=0, 1, b(n)*a(n-1)+a(n-2)))
    end:
seq(a(n), n=1..35);  # Alois P. Heinz, Aug 06 2013

Mathematica

b[n_] := b[n] = If[n < 2, n, r = Quotient[n, 2]; If[Mod[n, 2] == 0, b[r], b[r] + b[r + 1]]];
a[n_] := a[n] = If[n < 0, 0, If[n == 0, 1, b[n] a[n - 1] + a[n - 2]]];
Array[a, 35] (* Jean-François Alcover, Nov 10 2020, after Alois P. Heinz *)