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A007166
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Number of blobs with 2n+1 edges.
(Formerly M1777)
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0
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1, 1, 2, 7, 27, 118, 537, 2570, 12587, 63173, 322385, 1669144, 8742999, 46253727, 246771340, 1326236480, 7173280391, 39017312543, 213287030596, 1171140510636, 6456473371424, 35723687996130, 198311302682834, 1104189489401230
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OFFSET
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0,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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PROG
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(PARI) { s =y ; for(loop=1, 18, p = 1 ; forstep(i= 1, 2*loop-1, 2, sigmai = polcoeff(s, i, y) ; n=0 ; tmp = 0 ; while(i*n <=2*loop-1, ff = 1 ; for(k=1, n, ff *= (-sigmai-k+1)/k ; ) ; tmp += ff*(-y)^(i*n) ; n++ ; ) ; p *= tmp : ) ; b = y-s ; forstep(i=1, 2*loop-1, 2, b += polcoeff(p, i, y)*y^i ; ) ; print1(polcoeff(b, 2*loop-1, y), ", ") ; s = y ; for(r=0, loop-1, for(i=0, 2*loop+1, s += polcoeff(b^(3+2*r), i, y)*y^i ; ) ; ) ; ) ; } \\ R. J. Mathar, Apr 24 2006
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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