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A087224
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G.f. satisfies A(x) = f(x)^2 + x*A(x)*f(x)^3, where f(x)=sum(k>=0,x^((4^n-1)/3)).
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3
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1, 3, 7, 19, 50, 133, 352, 935, 2482, 6584, 17473, 46365, 123034, 326478, 866338, 2298895, 6100296, 16187616, 42955106, 113984740, 302467434, 802621041, 2129817812, 5651638433, 14997065388, 39795888008, 105601506802
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n) = A087221(3n+2).
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EXAMPLE
| Given f(x) = 1 +x +x^5 +x^21 +x^85 +x^341 +...
so that f(x)^2 = 1 +2x +x^2 +2x^5 +2x^6 +x^10 +2x^21 +...
and f(x)^3 = 1 +3x +3x^2 +x^3 +3x^5 +6x^6 +3x^7 +3x^10 +...
then A(x) = (1+2x+x^2+2x^5+...) + x*A(x)*(1+3x+3x^2+x^3+3x^5+...)
= 1 +3x +7x^2 +19x^3 +50x^4 +133x^5 +352x^6 +...
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PROG
| (PARI) a(n)=local(A, m); if(n<1, n==0, m=1; A=1+O(x); while(m<=3*n+3, m*=4; A=1/(1/subst(A, x, x^4)-x)); polcoeff(A, 3*n+2))
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CROSSREFS
| Cf. A087221, A087222, A087223.
Sequence in context: A147234 A171854 A182895 * A078059 A018031 A052948
Adjacent sequences: A087221 A087222 A087223 * A087225 A087226 A087227
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KEYWORD
| nonn
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AUTHOR
| Paul D. Hanna (pauldhanna(AT)juno.com), Aug 27 2003
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