A319233 Numbers k such that k^2 + 1 divides 2^k + 4.

0, 1, 8, 28, 32, 128, 2048, 8192, 23948, 131072, 524288, 8388608, 536870912, 2147483648, 137438953472

Offset: 1

Author

Altug Alkan, Sep 14 2018

Keywords

• nonn
• more

Comments

This sequence corresponds to numbers k such that k^2 + 1 divides 2^k + 2^m where m = 2 (A247220 (m = 0), A319216 (m = 1)).

a(16) > 10^12. - Hiroaki Yamanouchi, Sep 17 2018

Examples

			32 = 2^5 is a term since (2^(2^5) + 2^2)/((2^5)^2 + 1) = 2^22 - 2^12 + 2^2.
		

Crossrefs

Cf. A034785, A247220, A319216.

Programs

PARI

isok(n)=Mod(2, n^2+1)^n==-4;

Extensions

a(15) from Hiroaki Yamanouchi, Sep 17 2018