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A367717
G.f. A(x) satisfies A(x) = 1 / ((1 + x) * (1 - x * (1 + x + x^2) * A(x^3))).
2
1, 0, 2, 2, 5, 8, 16, 30, 57, 108, 206, 390, 741, 1407, 2670, 5068, 9622, 18262, 34666, 65806, 124911, 237109, 450092, 854368, 1621784, 3078519, 5843709, 11092672, 21056400, 39969753, 75871567, 144021302, 273384733, 518945611, 985075356, 1869894158, 3549478993
OFFSET
0,3
FORMULA
a(n) = (-1)^n + Sum_{k=0..n-1} a(floor(k/3)) * a(n-1-k).
PROG
(PARI) a_vector(n) = my(v=vector(n+1)); for(i=0, n, v[i+1]=(-1)^i+sum(j=0, i-1, v[j\3+1]*v[i-j])); v;
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 28 2023
STATUS
approved