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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A216579 Number of positive integer solutions to the equation a^2 + 10*b^2 = n. 2
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,91

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

MATHEMATICA

a[ n_] := If[ n < 1, 0, Length@Select[ Range@Sqrt[ n/10], IntegerQ@Sqrt[ n - 10 #] &]]; (* Michael Somos, Jan 10 2015 *)

PROG

(PARI) a(n)=sum(b=1, sqrtint((n-1)\10), issquare(n-10*b^2)) \\ Charles R Greathouse IV, Nov 19 2014

CROSSREFS

Cf. A020673, A033201.

Sequence in context: A112802 A137979 A160338 * A229878 A235145 A266342

Adjacent sequences:  A216576 A216577 A216578 * A216580 A216581 A216582

KEYWORD

nonn

AUTHOR

V. Raman, Sep 08 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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 19 13:01 EDT 2019. Contains 328222 sequences. (Running on oeis4.)