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A065101
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a(0) = c, a(1) = p*c^3; a(n+2) = p*c^2*a(n+1) - a(n), for p = 3, c = 2.
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1
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2, 24, 286, 3408, 40610, 483912, 5766334, 68712096, 818778818, 9756633720, 116260825822, 1385373276144, 16508218487906, 196713248578728, 2344050764456830, 27931895924903232, 332838700334381954
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OFFSET
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0,1
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LINKS
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J.-P. Ehrmann et al., Problem POLYA002, Integer pairs (x,y) for which (x^2+y^2)/(1+pxy) is an integer.
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FORMULA
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MATHEMATICA
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a[0] = c; a[1] = p*c^3; a[n_] := a[n] = p*c^2*a[n - 1] - a[n - 2]; p = 3; c = 2; Table[ a[n], {n, 0, 20} ]
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PROG
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(PARI): polya002(3, 2, 18). For definition of function polya002 see A052530.
(PARI) { p=3; c=2; k=p*c^2; for (n=0, 100, if (n>1, a=k*a1 - a2; a2=a1; a1=a, if (n, a=a1=k*c, a=a2=c)); write("b065101.txt", n, " ", a) ) } \\ Harry J. Smith, Oct 07 2009
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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