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

1,3

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

Links

Table of n, a(n) for n=1..15.

Example

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

Prog

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

Crossrefs

Cf. A034785, A247220, A319216.

Sequence in context: A201105 A184614 A006377 * A323198 A121739 A166729

Adjacent sequences: A319230 A319231 A319232 * A319234 A319235 A319236

Keyword

nonn,more

Author

Altug Alkan, Sep 14 2018

Extensions

a(15) from Hiroaki Yamanouchi, Sep 17 2018

Status

approved