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A241751
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a(n) = n^2 + 16.
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4
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16, 17, 20, 25, 32, 41, 52, 65, 80, 97, 116, 137, 160, 185, 212, 241, 272, 305, 340, 377, 416, 457, 500, 545, 592, 641, 692, 745, 800, 857, 916, 977, 1040, 1105, 1172, 1241, 1312, 1385, 1460, 1537, 1616, 1697, 1780, 1865, 1952, 2041, 2132, 2225, 2320
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OFFSET
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0,1
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LINKS
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FORMULA
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G.f.: (16 - 31*x + 17*x^2)/(1 - x)^3.
a(n) = a(-n) = 3*a(n-1) - 3*a(n-2) + a(n-3) = a(n-1) + 2*n - 1.
Sum_{n>=0} 1/a(n) = (1 + 4*Pi*coth(4*Pi))/32.
Sum_{n>=0} (-1)^n/a(n) = (1 + 4*Pi*cosech(4*Pi))/32. (End)
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MATHEMATICA
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Table[n^2 + 16, {n, 0, 60}]
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PROG
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(Magma) [n^2+16: n in [0..60]];
(Haskell)
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CROSSREFS
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Cf. similar sequences listed in A114962.
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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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