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 A227079 Solutions n to the Diophantine equation: n = (2*x^2 - 1)^2 = (6*y^2 - 5). 0
 1, 49, 289, 5041, 274266721 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS x = {1, 2, 3, 6, 91} = A180445(n). y = {1, 3, 7, 29, 6761} = A227077(n). (sqrt(2*sqrt(n) + 2) - 1)^2 is a Ramanujan-Nagell Square = {1, 9, 25, 121, 32761} = A227078(n). REFERENCES J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 181, p. 56, Ellipses, Paris 2008. L. J. Mordell, Diophantine Equations, Academic Press, NY, 1969, p. 205. LINKS Table of n, a(n) for n=0..4. Richard K. Guy, The Strong Law of Small Numbers (example #29). Eric Weisstein's World of Mathematics, Ramanujan's Square Equation CROSSREFS Cf. A060728, A180445, A227077, A227078. Sequence in context: A089552 A017354 A239607 * A251222 A250967 A245033 Adjacent sequences: A227076 A227077 A227078 * A227080 A227081 A227082 KEYWORD nonn,fini,full AUTHOR Raphie Frank, Aug 08 2013 STATUS approved

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Last modified December 6 01:57 EST 2023. Contains 367594 sequences. (Running on oeis4.)