A138673 a(n) = prime(n)^4 mod prime(n-1).

1, 1, 1, 4, 5, 9, 16, 9, 8, 16, 25, 34, 16, 41, 27, 24, 16, 15, 55, 16, 55, 19, 51, 2, 62, 16, 50, 16, 38, 109, 2, 117, 16, 131, 16, 88, 40, 93, 127, 85, 16, 45, 16, 63, 16, 40, 58, 33, 16, 27, 131, 16, 119, 41, 11, 244, 16, 212, 256, 16, 95, 33, 256, 16, 256

Offset

2,4

Links

Andrew Howroyd, Table of n, a(n) for n = 2..10000

Example

a(1) = 1 because 3^4 = 81 = 1 mod 2.
a(2) = 2 because 5^4 = 625 = 1 mod 3.

Mathematica

Table[Mod[Prime[n]^4, Prime[n - 1]], {n, 2, 50}]

Prog

(PARI) a(n) = lift(Mod(prime(n), prime(n-1))^4) \\ Andrew Howroyd, Oct 29 2025

Crossrefs

Cf. prime(n)^k mod prime(n-1): A001223, A038702, A138672, this sequence (k=4), A138674, A138675, A138676, A138677, A138678, A138679, A138680, A138681.

Sequence in context: A350695 A049860 A010382 * A087948 A010437 A020682

Adjacent sequences: A138670 A138671 A138672 * A138674 A138675 A138676

Keyword

nonn

Author

Artur Jasinski, Mar 26 2008

Extensions

Offset corrected and a(51) onward from Andrew Howroyd, Oct 29 2025

Status

approved