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2, 1, 0, -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16, -17, -18, -19, -20, -21, -22, -23, -24, -25, -26, -27, -28, -29, -30, -31, -32, -33, -34, -35, -36, -37, -38, -39, -40, -41, -42, -43, -44, -45, -46, -47, -48, -49, -50, -51, -52, -53, -54, -55
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,1
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COMMENTS
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a(n) is the Euler characteristic of one-sided surface of genus n (see Courant and Herbert). - Stefano Spezia, Sep 10 2022
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LINKS
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FORMULA
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G.f.: (2-3x)/(1-x)^2.
E.g.f.: exp(x)*(2-x). (End)
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MATHEMATICA
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2-Range[0, 60] (* or *) LinearRecurrence[{2, -1}, {2, 1}, 60] (* Harvey P. Dale, Feb 23 2023 *)
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PROG
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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STATUS
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approved
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