login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A338256 Generalized Markoff numbers: union of numbers a, b, c, d, e satisfying the Markoff(5) equation a^2 + b^2 + c^2 + d^2 + e^2 = a*b*c*d*e. 0
1, 3, 4, 5, 9, 12, 23, 31, 33, 35, 44, 57, 60, 81, 107, 123, 157, 179, 204, 212, 273, 293, 311, 369, 391, 411, 417, 459, 555, 620, 657, 679, 1076, 1115, 1187, 1259, 1275, 1308, 1377, 1453, 1713, 1813, 1979, 2508, 2604, 2673, 2764, 2817, 2885, 3419, 3475, 3804, 3849 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Every term of A229240 is a term of this sequence.
Also, union of positive integers satisfying Hurwitz equation (x_1)^2 + (x_2)^2 + ... + (x_n)^2 = z * x_1 * x_2 * ... * x_n for z=1 and n=5.
LINKS
EXAMPLE
{1259,35,4,3,3} is a solution and that is why 3,4,35,1259 belong to the sequence.
MATHEMATICA
div={1, 3}; limit=10^4; Monitor[Do[m=div[[{a, b, c, d}]]; m1=Times@@m; m2=Tr[m^2]; s=Sqrt[m1^2-4m2]; x1=(m1-s)/2; x2=(m1+s)/2; If[IntegerQ[x1]&&x2<limit, AppendTo[div, {x1, x2}]]; div=Union@Flatten@div, {n, 5}, {a, l=Length@div}, {b, a}, {c, b}, {d, c}], {"stops when", l-a, "is equal to 0"}]; div
CROSSREFS
Sequence in context: A166976 A240056 A235396 * A237132 A080633 A360374
KEYWORD
nonn
AUTHOR
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 18 03:01 EDT 2024. Contains 371767 sequences. (Running on oeis4.)