login
This site is supported by donations to The OEIS Foundation.

 

Logo

"Email this user" was broken Aug 14 to 9am Aug 16. If you sent someone a message in this period, please send it again.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A025367 Numbers that are the sum of 4 nonzero squares in 2 or more ways. 1
28, 31, 34, 36, 37, 39, 42, 43, 45, 47, 49, 50, 52, 54, 55, 57, 58, 60, 61, 63, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 87, 90, 91, 92, 93, 94, 95, 97, 98, 99, 100, 102, 103, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

Index entries for sequences related to sums of squares

MAPLE

N:= 1000: # to get all terms <= N

V:= Vector(N):

for x from 1 while x^2 +3 <= N do

for y from 1 to x while x^2 + y^2 + 2 <= N do

  for z from 1 to y while x^2 + y^2 + z^2 + 1 <= N do

    for w from 1 to z while x^2 + y^2 + z^2 + w^2 <= N do

       t:= x^2 + y^2 + z^2 + w^2;

       V[t]:= V[t]+1;

od od od od:

select(t -> V[t] >= 2, [$1..N]); # Robert Israel, Jul 05 2017

MATHEMATICA

Select[Range@ 200, 2 == Length@ Quiet@ IntegerPartitions[#, {4}, Range[Sqrt@ #]^2, 2] &] (* Giovanni Resta, Jul 05 2017 *)

CROSSREFS

Sequence in context: A067913 A116566 A057483 * A121018 A232727 A232766

Adjacent sequences:  A025364 A025365 A025366 * A025368 A025369 A025370

KEYWORD

nonn

AUTHOR

David W. Wilson

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified August 17 03:51 EDT 2017. Contains 290631 sequences.