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A136017
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a(n) = 36n^2 - 1.
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11
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35, 143, 323, 575, 899, 1295, 1763, 2303, 2915, 3599, 4355, 5183, 6083, 7055, 8099, 9215, 10403, 11663, 12995, 14399, 15875, 17423, 19043, 20735, 22499, 24335, 26243, 28223, 30275, 32399, 34595, 36863, 39203, 41615, 44099, 46655, 49283, 51983
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OFFSET
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1,1
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COMMENTS
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The least common multiple of 6*n+1 and 6*n-1. - Colin Barker, Feb 11 2017
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LINKS
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FORMULA
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O.g.f.: x*(-35-38*x+x^2)/(-1+x)^3 = 1-35/(-1+x)-108/(-1+x)^2-72/(-1+x)^3 . - R. J. Mathar, Dec 12 2007
E.g.f.: 1 + (36 x^2 + 26 x - 1) exp(x). - Robert Israel, Jun 09 2016
Sum_{n>=1) 1/a(n) = 1/2 - sqrt(3)*Pi/12. - Amiram Eldar, Jun 27 2020
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MATHEMATICA
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Table[36n^2 - 1, {n, 1, 100}]
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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