A231331 Number of distinct terms in row n of triangle A230871.

1, 1, 2, 3, 6, 10, 20, 35, 74, 130, 258, 473, 1007, 1830, 3912, 7093, 15233, 27831, 60458, 109555, 239039, 433654, 946849, 1709524, 3746021, 6750928

Offset: 0

Author

Reinhard Zumkeller, Nov 07 2013

Keywords

• nonn
• more

Comments

Length of row n in triangle A231330.

Crossrefs

Cf. A231335.

Programs

Haskell

a231331 = length . a231330_row

PARI

vf(v) = #Set(v);
lista(nn) = my(va=[0], vb=[1]); print1(vf(va), ", "); print1(vf(vb), ", "); for (n=2, nn, v = vector(2^(n-1), k, j=(k+1)\2; i=(j+1)\2; y=vb[j]; x=va[i]; if (k%2, y+x, 3*y-x)); print1(vf(v), ", "); va = vb; vb = v;); \\ Michel Marcus, Sep 23 2023

Extensions

a(23)-a(25) from Michel Marcus, Sep 23 2023