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A075276 Generalized Markoff numbers: union of numbers a, b, c, d satisfying the Markoff(4) equation a^2 + b^2 + c^2 + d^2 = 4abcd. +0
2
1, 3, 11, 41, 131, 153, 571, 1561, 1803, 2131, 5761, 7953, 17291, 18601, 25091, 79291, 221651, 253353, 295681, 349451, 817961, 2282281, 2453891, 3018753, 3252611, 4114771, 4867203, 15355651, 27181441, 33206403, 99665321 (list; graph; listen)
OFFSET

1,2

FORMULA

If (a, b, c, d) satisfies Markoff(4) equation, then so does (a, b, c, 4abc - d) and 4abc - d = (a^2 + b^2 + c^2)/d.

EXAMPLE

Some solutions to Markoff(4) equation a^2 + b^2 + c^2 + d^2 = 4abcd are (1,1,1,1), (1,1,1,3), (1,1,3,11), (1,3,11,131), (3,11,131,17291), (1,1,11,41), (1,11,41,1803), (1,1,41,153), (1,3,131,1561), (1,11,131,5761), (1,1,153,571), (1,1,571,2131), (1,1,2131,7953), (1,3,1561,18601).

CROSSREFS

Cf. A002559.

Sequence in context: A149065 A131526 A073622 this_sequence A086972 A077831 A032952

Adjacent sequences: A075273 A075274 A075275 this_sequence A075277 A075278 A075279

KEYWORD

easy,nonn

AUTHOR

Paul D. Hanna (pauldhanna(AT)juno.com), Sep 12 2002

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Last modified November 24 23:16 EST 2009. Contains 167481 sequences.


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