1,1

P. J. van Albada, Factorization of the numbers n^2+1, Nieuw Arch. Wisk., 16 (1998), pp. 191-197.

Table of n, a(n) for n=1..77.

Table[Count[4 #^2 + 1 & /@ Range[n^2 + 1, (n + 1)^2 - 1], _?PrimeQ], {n, 77}] (* Jayanta Basu, Jun 27 2013 *)

Sequence in context: A107918 A242392 A002963 * A283104 A109747 A105612

Adjacent sequences: A046674 A046675 A046676 * A046678 A046679 A046680

nonn

Floor van Lamoen

approved