A218710 a(n) is smallest number such that a(n)^2 + 1 is divisible by 17^n.

0, 4, 38, 1985, 27493, 390112, 390112, 96940388, 3379649772, 24306922095, 450044583893, 5597937117454, 28673959190179, 3524407382568745, 13428985415474682, 13428985415474682, 5711417117604156904, 91610966633729580058, 6709533061724423693474

Offset: 0

Author

Michel Lagneau, Nov 04 2012

Keywords

• nonn

Examples

			a(4) = 27493 because 27493^2+1 =  2 * 5 ^ 2 * 17 ^ 4 * 181.
		

Crossrefs

Cf. A002522, A049532, A034939, A218709.

Programs

Mathematica

b=4;n17=17;jo=Join[{0,b},Table[n17=17*n17;b=PowerMod[b,17,n17];b=Min[b,n17-b],{99}]]