The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A239444 Sum{gcd(k^2 + t^2, n)* cos(2*Pi*(k^2 + t^2)/n)): 0
 1, 2, -1, 8, 41, -2, -1, 32, 81, 82, -1, -8, 313, -2, -41, 128, 545, 162, -1, 328, 1, -2, -1, -32, 1425, 626, -81, -8, 1625, -82, -1, 512, 1, 1090, -41, 648, 2665, -2, -313, 1312, 3281, 2, -1, -8, 3321, -2, -1, -128, 2401, 2850, -545, 2504, 5513, -162, -41, -32, 1, 3250, -1, -328, 7321 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..61. MATHEMATICA GGG[n_] := Sum[GCD[k^2 + t^2, n] Cos[2 Pi (k^2 + t^2)/n], {k, 1, n}, {t, 1, n}]; Table[Round[GGG[n]], {n, 1, 111}] CROSSREFS Sequence in context: A214731 A079899 A333469 * A224090 A013327 A359625 Adjacent sequences: A239441 A239442 A239443 * A239445 A239446 A239447 KEYWORD sign AUTHOR José María Grau Ribas, Mar 22 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 29 02:45 EDT 2023. Contains 365749 sequences. (Running on oeis4.)