A277126 Positive integers n such that 3^n == 7 (mod n).

1, 2, 295, 883438, 252027511, 7469046275, 26782373099, 53191768475, 55246802458, 819613658855, 893727887879978

Offset: 1

Author

Seiichi Manyama, Oct 06 2016

Keywords

• nonn
• more

Comments

No other terms below 10^15. A larger term: 9135884036634915191945452485106476242. - Max Alekseyev, Oct 12 2016

Terms are not divisible by 127 (Alekseyev 2016).

Examples

			3 == 7 mod 1, so 1 is a term;
9 == 7 mod 2, so 2 is a term.
		

References

• M. A. Alekseyev. "Problem 4101". Crux Mathematicorum 42:1 (2016), 28.

Crossrefs

Solutions to 3^n == k (mod n): A277340 (k=-11), A277289 (k=-7), A277288 (k=-5), A015973 (k=-2), A015949 (k=-1), A067945 (k=1), A276671 (k=2), A276740 (k=5), this sequence (k=7), A277274 (k=11).

Programs

PARI

isok(n) = Mod(3, n)^n == 7; \\ Michel Marcus, Oct 06 2016

Extensions

a(5) from Joerg Arndt, Oct 06 2016

a(6)-a(11) from Max Alekseyev, Oct 12 2016