A112983 a(n) = 2^(n+1) mod n.

0, 0, 1, 0, 4, 2, 4, 0, 7, 8, 4, 8, 4, 8, 1, 0, 4, 2, 4, 12, 16, 8, 4, 8, 14, 8, 25, 4, 4, 8, 4, 0, 16, 8, 1, 20, 4, 8, 16, 32, 4, 2, 4, 32, 34, 8, 4, 32, 11, 48, 16, 32, 4, 2, 31, 8, 16, 8, 4, 32, 4, 8, 16, 0, 64, 62, 4, 32, 16, 18, 4, 56, 4, 8, 61, 32, 36, 50, 4

Offset

1,5

Links

T. D. Noe, Table of n, a(n) for n = 1..10000

Formula

a(n) = A106262(2*n-1, n-2). - G. C. Greubel, Jan 11 2023

Example

a(3) = 2^4 mod 3 = 16 mod 3 = 1.

Mathematica

Table[PowerMod[2, n + 1, n], {n, 100}] (* T. D. Noe, Aug 13 2012 *)

Prog

(Python)
print([2**(n+1) % n for n in range(1, 77)])
# Alex Ratushnyak, Aug 12 2012
(Magma) [Modexp(2, n+1, n): n in [1..120]]; // G. C. Greubel, Jan 11 2023
(SageMath) [power_mod(2, n+1, n) for n in range(1, 120)] # G. C. Greubel, Jan 11 2023

Crossrefs

Cf. A106262, A212844.

Sequence in context: A248252 A117238 A197291 * A332330 A068454 A090976

Adjacent sequences: A112980 A112981 A112982 * A112984 A112985 A112986

Keyword

easy,nonn

Author

Paul Barry, Oct 08 2005

Extensions

Name, data and offset corrected by Alex Ratushnyak, Aug 12 2012

Status

approved