A083530 a(n) = 7^n mod (2*n).

1, 1, 1, 1, 7, 1, 7, 1, 1, 9, 7, 1, 7, 21, 13, 1, 7, 1, 7, 1, 7, 5, 7, 1, 7, 49, 1, 49, 7, 49, 7, 1, 13, 49, 63, 1, 7, 49, 31, 1, 7, 49, 7, 25, 37, 49, 7, 1, 49, 49, 37, 9, 7, 1, 43, 49, 1, 49, 7, 1, 7, 49, 91, 1, 37, 37, 7, 89, 67, 49, 7, 1, 7, 49, 43, 121, 105, 25, 7, 1, 1, 49, 7, 49, 147, 49

Offset: 1

Author

Labos Elemer, Apr 30 2003

Keywords

• easy
• nonn

Examples

			For n = 5, a(5) = 7 because 7^5 = 16807 = 1680*10 + 7, that is 7^5 == 7 (mod 2*5).
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000079, A000244, A000351, A000420, A082511, A083528, A083529.

Programs

Mathematica

Table[Mod[7^w, 2*w], {w, 1, 100}]

PARI

a(n)=lift(Mod(7,2*n)^n) \\ Charles R Greathouse IV, Oct 03 2016