A277289 Positive integers n such that n | (3^n + 7).

1, 2, 4, 5, 8, 25, 44, 4664, 6568, 1353025, 2919526, 5709589, 7827725, 64661225, 85132756, 153872408, 743947534, 34304296003, 38832409867, 40263727492, 1946603375348, 2469908330348, 64471909888247, 274267749806485, 888906849689897, 896501949422459

Offset: 1

Author

Seiichi Manyama, Oct 09 2016

Keywords

• nonn

Comments

No other terms below 10^15. - Max Alekseyev, Oct 14 2016

492385451091805616444 is a term.

Examples

			3^25 + 7 = 847288609450 = 25 * 33891544378, so 25 is a term.
		

Crossrefs

Solutions to 3^n == k (mod n): A277340 (k=-11), this sequence (k=-7), A277288 (k=-5), A015973 (k=-2), A015949 (k=-1), A067945 (k=1), A276671 (k=2), A276740 (k=5), A277126 (k=7), A277274 (k=11).

Programs

PARI

is(n)=Mod(3,n)^n==-7; \\ Joerg Arndt, Oct 09 2016

Python

A277289_list = [1,2,4,5]+[n for n in range(6,10**6) if pow(3,n,n)==n-7] # Chai Wah Wu, Oct 12 2016

Extensions

a(17) from Joerg Arndt, Oct 09 2016

a(18)-a(20) from Chai Wah Wu, Oct 12 2016

a(21)-a(26) from Max Alekseyev, Oct 14 2016