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

0,3

Comments

Length of row n in triangle A231330.

Links

Table of n, a(n) for n=0..25.

Prog

(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

Crossrefs

Cf. A231335.

Sequence in context: A036557 A173125 A047131 * A374635 A008927 A331488

Adjacent sequences: A231328 A231329 A231330 * A231332 A231333 A231334

Keyword

nonn,more

Author

Reinhard Zumkeller, Nov 07 2013

Extensions

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

Status

approved