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Number of distinct terms in row n of triangle A230871.
4

%I #8 Sep 23 2023 08:52:26

%S 1,1,2,3,6,10,20,35,74,130,258,473,1007,1830,3912,7093,15233,27831,

%T 60458,109555,239039,433654,946849,1709524,3746021,6750928

%N Number of distinct terms in row n of triangle A230871.

%C Length of row n in triangle A231330.

%o (Haskell)

%o a231331 = length . a231330_row

%o (PARI) vf(v) = #Set(v);

%o 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

%Y Cf. A231335.

%K nonn,more

%O 0,3

%A _Reinhard Zumkeller_, Nov 07 2013

%E a(23)-a(25) from _Michel Marcus_, Sep 23 2023