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Search: id:A128577
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| 1, 2, 9, 64, 624, 7736, 116416, 2060808, 41952600, 965497440, 24786054816, 702201877920, 21761251764672, 732269872931712, 26589359234860560, 1036241806935453696, 43142510740036313088, 1911022260200150482944
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OFFSET
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0,2
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COMMENT
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A128318 equals row 0 of table A128570.
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FORMULA
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G.f.: A(x) = [1 + x*R(x,1)^2]^2, where R(x,1) = 1 + 2*x*R(x,2)^2, R(x,2) = 1 + 3*x*R(x,3)^2, ..., R(x,n) = 1 + (n+1)*x*R(x,n+1)^2, ... and R(x,n) is the g.f. of row n of table A128570.
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PROGRAM
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(PARI) {a(n)=local(A=1+(n+1)*x); for(j=0, n, A=1+(n+1-j)*x*A^2 +x*O(x^n)); polcoeff(A^2, n)}
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CROSSREFS
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Cf. A128570 (triangle), rows: A128318, A128571, A128572, A128573, A128574, A128575, A128576; A128578 (main diagonal), A128579 (antidiagonal sums).
Sequence in context: A059281 A036775 A141209 this_sequence A052514 A036776 A036777
Adjacent sequences: A128574 A128575 A128576 this_sequence A128578 A128579 A128580
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Mar 11 2007
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