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A324270
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a(n) = 13*7^(7*n).
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0
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13, 10706059, 8816899947037, 7261096233082692091, 5979824975081619492698413, 4924642999453642161875329137259, 4055655269699050826917294183685688637, 3340006507773765415151949203915063077180891, 2750638979431530091290481703239822791770782516813, 2265269477037980585971637173331233381403285546243728459
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OFFSET
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0,1
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COMMENTS
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x = a(n) and y = A324266(n) satisfy the Lebesgue-Ramanujan-Nagell equation x^2 + 7^(14*n+3) = 4*y^7 (see Theorem 2.1 in Chakraborty, Hoque and Sharma).
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LINKS
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FORMULA
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O.g.f.: 13/(1 - 823543*x).
E.g.f.: 13*exp(823543*x).
a(n) = 823543*a(n-1) for n > 0.
a(n) = 13*823543^n.
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EXAMPLE
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For a(0) = 13 and A324266(0) = 2, 13^2 + 7^3 = 512 = 4*2^7.
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MAPLE
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a:=n->13*823543^n: seq(a(n), n=0..20);
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MATHEMATICA
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13 823543^Range[0, 20]
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PROG
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(GAP) List([0..20], n->13*823543^n);
(Magma) [13*823543^n: n in [0..20]];
(PARI) a(n) = 13*823543^n;
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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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