The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A291850 Numbers k such that k^2 is the sum of two positive 5th powers. 0
 8, 256, 1944, 6655, 8192, 25000, 35937, 62208, 134456, 212960, 262144, 344605, 453962, 472392, 692759, 800000, 1149984, 1288408, 1617165, 1990656, 2970344, 4302592, 6075000, 6814720, 8388608, 8732691, 11358856, 14526784, 15116544, 19808792, 20796875, 22168288 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS If a^5 + b^5 = m, then (ma)^5 + (mb)^5 = m^6 = (m^3)^2 is square. Therefore A003347(n)^3 is terms of this sequence. When k in this sequence, k * (n^5) (n = 2, 3, ... ) is also in this sequence. LINKS EXAMPLE 8^2 = 2^5 + 2^5, so 8 is in the sequence. 6655^2 = 22^5 + 33^5, so 6655 is in the sequence. MATHEMATICA lst={}; Do[If[IntegerQ[(n^2-a^5)^(1/5)], AppendTo[lst, n^2]], {n, 7000}, {a, n^2/2)^(1/5)}]; lst CROSSREFS Cf. A000404, A004431, A003325, A050801, A003336, A003347. Sequence in context: A034674 A317511 A300176 * A130034 A128787 A013824 Adjacent sequences:  A291847 A291848 A291849 * A291851 A291852 A291853 KEYWORD nonn AUTHOR XU Pingya, Sep 04 2017 STATUS approved

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

Last modified June 13 11:36 EDT 2021. Contains 344990 sequences. (Running on oeis4.)