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A275766
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a(n) = (5^(2*(n + 1)) - 1)/4.
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1
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156, 3906, 97656, 2441406, 61035156, 1525878906, 38146972656, 953674316406, 23841857910156, 596046447753906, 14901161193847656, 372529029846191406, 9313225746154785156, 232830643653869628906, 5820766091346740722656, 145519152283668518066406
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OFFSET
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1,1
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COMMENTS
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It seems that these terms are the only numbers n such that n and n + 1 are in A053696.
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LINKS
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FORMULA
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a(n) = 26*a(n-1) - 25*a(n-2), a(1) = 156, a(2) = 3906.
G.f.: 6*x*(26-25*x) / ((1-x)*(1-25*x)). - Colin Barker, Aug 24 2016
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EXAMPLE
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3906 written in base 5 is 111111 and 3907 written in base 62 is 111.
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MATHEMATICA
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Table[(5^(2 (n + 1)) - 1)/4, {n, 16}] (* or *)
Rest@ CoefficientList[Series[6 x (26 - 25 x)/((1 - x) (1 - 25 x)), {x, 0, 16}], x] (* Michael De Vlieger, Aug 28 2016 *)
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PROG
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(PARI) Vec(6*x*(26-25*x)/((1-x)*(1-25*x)) + O(x^20)) \\ Colin Barker, Aug 24 2016
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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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