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 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

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