A075405 a(n)^2 is the square obtained in A075404 (or 0 if no such square exists).

70, 0, 5, 0, 0, 0, 92, 0, 106, 0, 2001863, 0, 652, 0, 679, 0, 138, 77, 0, 29, 724, 413, 0, 0, 182, 0, 253, 385, 0, 1612, 0, 8687, 0, 0, 0, 0, 0, 143, 0, 0, 0, 0, 0, 274, 0, 0, 0, 0, 0, 1281, 0, 1012, 0, 0, 121268, 0, 0, 56855, 0, 440, 0, 0, 0, 3069, 2725, 0, 655, 0, 0, 0, 0, 0, 1525, 4035066, 0, 430, 0, 0, 0, 0, 0, 0, 2619, 0, 0, 0, 795, 0, 0, 0, 3465, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset

1,1

References

See A180244.

Links

Table of n, a(n) for n=1..100.

Example

a(1) = 70 because 1^2+...+24^2 = a(1)^2 = 70^2.

Mathematica

s[n_, k_]:=Module[{m=n+k-1}, (m(m+1)(2m+1)-n(n-1)(2n-1))/6]; mx=40000; Table[k=2; While[k<mx && !IntegerQ[Sqrt[s[n, k]]], k++]; If[k==mx, 0, Sqrt[s[n, k]]], {n, 100}]

Crossrefs

Cf. A000330, A075404, A075406.

Sequence in context: A136114 A365913 A278074 * A365914 A177808 A327024

Adjacent sequences: A075402 A075403 A075404 * A075406 A075407 A075408

Keyword

nonn

Author

Zak Seidov, Sep 13 2002

Extensions

Corrected and extended by Lior Manor Sep 19 2002

Corrected and edited by T. D. Noe, Jan 21 2011

Status

approved