95371domain: NAppears in sequencesNumbers k such that the period of the continued fraction for sqrt(k) contains exactly 83 ones.at n=3A031851n-th 4k+1 prime times n-th 4k-1 prime.at n=31A048630The sum a(n) + a(n+1) is visible around the comma that follows a(n+1). See the Comments and Example sections for details.at n=13A334829