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A036255
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Number of inequivalent strings of 2n+1 digits, when 2 strings are equivalent if turning 1 upside down gives the other.
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2
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9, 945, 98475, 9961125, 999024375, 99975590625, 9999389671875, 999984741328125, 99999618530859375, 9999990463259765625, 999999761581435546875, 99999994039535595703125, 9999999850988388427734375, 999999996274709703369140625, 99999999906867742547607421875
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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REFERENCES
| De Bruijn, Polya's theory of counting, in Beckenbach, ed., Applied Combinatorial Math., Wiley, 1964 (p. 182).
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FORMULA
| 10^(2*n+1)-5^(2*n+1)/2+3*5^n/2.
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CROSSREFS
| Cf. A036257, A036258.
Sequence in context: A069054 A015107 A024124 * A070233 A087590 A048561
Adjacent sequences: A036252 A036253 A036254 * A036256 A036257 A036258
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KEYWORD
| nonn,easy,base
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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