A166376 Triangle in which n-th row (n>1) gives prime factors of n^2 + 1 with repetition.

2, 5, 2, 5, 17, 2, 13, 37, 2, 5, 5, 5, 13, 2, 41, 101, 2, 61, 5, 29, 2, 5, 17, 197, 2, 113, 257, 2, 5, 29, 5, 5, 13, 2, 181, 401, 2, 13, 17, 5, 97, 2, 5, 53, 577, 2, 313, 677, 2, 5, 73, 5, 157, 2, 421, 17, 53, 2, 13, 37, 5, 5, 41

Offset: 1

Author

Michael B. Porter, Oct 13 2009

Keywords

• nonn
• tabf

Examples

			Since 13^2+1 = 170 = 2*5*17, the three terms 2, 5, 17 appear in the sequence.
		

Crossrefs

Cf. A027746 A002522

Programs

PARI

row(n)={m=n^2+1;while(m!=1,p=factor(m)[1,1];print(p);m=m/p)}