A218709 a(n) is smallest number such that a(n)^2 + 1 is divisible by 13^n.

0, 5, 70, 239, 239, 143044, 1999509, 6826318, 6826318, 822557039, 52199939826, 603633907222, 11356596271444, 11356596271444, 1828607235824962, 13920898306972194, 13920898306972194, 2675587335039691558, 49226908181248336040, 513050126578538629605

Offset

0,2

Links

Table of n, a(n) for n=0..19.

Example

a(4) = 239 because 239^2+1 = 2*13^4.

Mathematica

b=5; n13=13; jo=Join[{0, b}, Table[n13=13*n13; b=PowerMod[b, 13, n13]; b=Min[b, n13-b], {99}]]

Crossrefs

Cf. A002522, A049532, A034939.

Sequence in context: A145632 A299318 A051538 * A286840 A034944 A064046

Adjacent sequences: A218706 A218707 A218708 * A218710 A218711 A218712

Keyword

nonn

Author

Michel Lagneau, Nov 04 2012

Status

approved