109513domain: NAppears in sequencesNumbers n such that n-1, n and n+1 can be expressed as a sum of 2 squares in at least 2 ways.at n=22A091459a(n) = (Sum_{k=1..A047380(n)} k^6) / (Sum_{k=1..A047380(n)} k^2).at n=12A133180a(n) = 1 + 27n + 252n^2 + 882n^3 + 1029n^4.at n=3A134158a(n) = 72*n^2 + 1.at n=39A158740