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 A077248 Combined Diophantine Chebyshev sequences A077246 and A077244. 1
 2, 3, 13, 22, 102, 173, 803, 1362, 6322, 10723, 49773, 84422, 391862, 664653, 3085123, 5232802, 24289122, 41197763, 191227853, 324349302, 1505533702, 2553596653, 11853041763, 20104423922, 93318800402 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS 3*a(n)^2 - 5*b(n)^2 = 7, with the companion sequence b(n)= A077247(n). LINKS FORMULA a(2*k)= A077246(k) and a(2*k+1)= A077244(k), k>=0. G.f.: (1-x)*(2+x)*(1+2*x)/(1-8*x^2+x^4). EXAMPLE 13 = a(2) = sqrt((5*A077247(2)^2 + 7)/3) = sqrt((5*10^2 + 7)/3)= sqrt(169) = 13. CROSSREFS Sequence in context: A139563 A019226 A138699 * A137248 A136260 A181521 Adjacent sequences:  A077245 A077246 A077247 * A077249 A077250 A077251 KEYWORD nonn,easy AUTHOR Wolfdieter Lang, Nov 08 2002 STATUS approved

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