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

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

Offset

1,2

Comments

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

Terms are not divisible by 127 (Alekseyev 2016).

References

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

Links

Table of n, a(n) for n=1..11.

Example

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

Prog

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

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).

Sequence in context: A057746 A362517 A132518 * A273198 A359208 A199946

Adjacent sequences: A277123 A277124 A277125 * A277127 A277128 A277129

Keyword

nonn,more

Author

Seiichi Manyama, Oct 06 2016

Extensions

a(5) from Joerg Arndt, Oct 06 2016

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

Status

approved