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A053716
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a(n) = 1111111 in base n.
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18
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7, 127, 1093, 5461, 19531, 55987, 137257, 299593, 597871, 1111111, 1948717, 3257437, 5229043, 8108731, 12204241, 17895697, 25646167, 36012943, 49659541, 67368421, 90054427, 118778947, 154764793, 199411801, 254313151, 321272407, 402321277, 499738093
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OFFSET
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1,1
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COMMENTS
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Evaluation of the seventh cyclotomic polynomial at n. - Joerg Arndt, Aug 27 2015
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LINKS
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FORMULA
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a(n) = n^6+n^5+n^4+n^3+n^2+n+1 = (n^7-1)/(n-1).
G.f.: -x*(x^6-6*x^5+57*x^4+232*x^3+351*x^2+78*x+7)/(x-1)^7. [Colin Barker, Oct 29 2012]
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EXAMPLE
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a(3)=1093 because 1111111 base 3=729+243+81+27+9+3+1=121.
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MAPLE
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numtheory[cyclotomic](7, n) ;
end proc:
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MATHEMATICA
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CoefficientList[Series[-(x^6 - 6 x^5 + 57 x^4 + 232 x^3 + 351 x^2 + 78 x + 7)/(x - 1)^7, {x, 0, 40}], x] (* Vincenzo Librandi, Feb 08 2014 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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