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A116165
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a(n) = 7^n * n*(n+1).
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1
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0, 14, 294, 4116, 48020, 504210, 4941258, 46118408, 415065672, 3631824630, 31072277390, 261007130076, 2159240803356, 17633799894074, 142426845298290, 1139414762386320, 9039357114931472, 71184937280085342, 556917450485373558
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OFFSET
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0,2
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LINKS
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FORMULA
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Sum_{n>=1} 1/a(n) = 1 - 6*log(7/6).
Sum_{n>=1} (-1)^(n+1)/a(n) = 8*log(8/7) - 1. (End)
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MATHEMATICA
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PROG
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(Magma) [(n^2+n)*7^n: n in [0..30]]; /* or */ I:=[0, 14, 294]; [n le 3 select I[n] else 21*Self(n-1)-147*Self(n-2)+343*Self(n-3): n in [1..30]]; // Vincenzo Librandi, Feb 28 2013
(Sage) [7^n*n*(n+1) for n in (0..30)] # G. C. Greubel, May 11 2019
(GAP) List([0..30], n-> 7^n*n*(n+1)) # G. C. Greubel, May 11 2019
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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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