This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A213024 The number of solutions to x^2 + y^2 + 2*z^2 = n in positive integers x,y,z. 3
 0, 0, 0, 0, 1, 0, 0, 2, 0, 0, 2, 0, 2, 2, 0, 2, 1, 0, 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 6, 0, 0, 4, 0, 2, 4, 2, 3, 4, 2, 2, 2, 0, 6, 4, 2, 4, 0, 4, 2, 4, 2, 0, 8, 2, 2, 6, 0, 2, 8, 2, 6, 4, 0, 6, 1, 0, 4, 6, 4, 4, 6, 2, 2, 6, 2, 4, 8, 4, 0, 4, 2, 2, 10, 4, 6, 4, 2, 6, 2, 2, 8, 6, 6, 6, 0, 2, 0, 8, 6, 2, 9 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,8 REFERENCES Mohammad K. Azarian, Diophantine Pair, Problem B-881, Fibonacci Quarterly, Vol. 37, No. 3, August 1999, pp. 277-278.  Solution published in Vol. 38, No. 2, May 2000, pp. 183-184. LINKS FORMULA a(n) = ( A014455(n) - 2*A033715(n) - A004018(n) + A000122(n/2) + 2*A000122(n) - A000007(n) )/8. G.f.: T(x)^2 * T(x^2) where T(x) = sum(k>=1, x^(k^2)). [Joerg Arndt, Oct 01 2012] PROG (PARI) N=166; x='x+O('x^N); T(x)=sum(k=1, 1+sqrtint(N), x^(k*k) ); gf=T(x)^2 * T(x^2); v=Vec('a0 + gf );  v[1]=0;  v /* Joerg Arndt, Oct 01 2012 */ CROSSREFS Cf. A156384 Sequence in context: A308046 A289323 A086937 * A291289 A095759 A260309 Adjacent sequences:  A213021 A213022 A213023 * A213025 A213026 A213027 KEYWORD nonn AUTHOR Max Alekseyev, Sep 29 2012 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 October 22 09:56 EDT 2019. Contains 328315 sequences. (Running on oeis4.)