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A367659 G.f. A(x) satisfies A(x) = 1 / (1 - x - x * A(x^3)). 9
1, 2, 4, 8, 18, 40, 88, 196, 436, 968, 2152, 4784, 10632, 23634, 52536, 116776, 259576, 577000, 1282576, 2850968, 6337264, 14086744, 31312644, 69603152, 154716976, 343911796, 764462500, 1699281320, 3777238312, 8396213840, 18663478600, 41486012712, 92216959616 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
FORMULA
a(0) = 1; a(n) = a(n-1) + Sum_{k=0..floor((n-1)/3)} a(k) * a(n-1-3*k).
a(0) = 1, a(1) = 2, a(2) = 4; a(n) = a(n-3) + Sum_{k=0..n-1} a(floor(k/3)) * a(n-1-k).
PROG
(PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, (i-1)\3, v[j+1]*v[i-3*j])); v;
CROSSREFS
Sequence in context: A086585 A329971 A052910 * A000967 A288309 A096813
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 26 2023
STATUS
approved

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Last modified May 27 07:52 EDT 2024. Contains 372850 sequences. (Running on oeis4.)