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A154560
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(n+3)^2*n/2 + 1.
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4
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1, 9, 26, 55, 99, 161, 244, 351, 485, 649, 846, 1079, 1351, 1665, 2024, 2431, 2889, 3401, 3970, 4599, 5291, 6049, 6876, 7775, 8749, 9801, 10934, 12151, 13455, 14849, 16336, 17919, 19601, 21385, 23274, 25271, 27379, 29601, 31940, 34399, 36981
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OFFSET
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0,2
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COMMENTS
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8*a(n) is the y value of a solution (x, y) to the Diophantine equation 2*x^3+12*x^2 = y^2. The corresponding x value is A152811(n+1).
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LINKS
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FORMULA
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G.f.: (1+5*x-4*x^2+x^3)/(1-x)^4.
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EXAMPLE
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a(5) = (5+3)^2*5/2+1 = 64*5/2+1 = 161.
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PROG
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(PARI) {for(n=0, 40, print1((n+3)^2*n/2+1, ", "))}
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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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