A176083 a(n) = 2^(2n-2) mod prime(2n).

1, 4, 3, 7, 24, 25, 11, 7, 22, 12, 9, 1, 5, 69, 1, 62, 41, 16, 133, 89, 39, 3, 162, 66, 121, 12, 4, 109, 163, 85, 135, 52, 251, 8, 14, 6, 154, 126, 167, 284, 149, 158, 254, 110, 318, 23, 75, 23, 59, 279, 478, 513, 290, 58, 256, 345, 347, 25, 58, 361, 672, 681, 673, 697, 669, 609, 278, 739, 355, 529, 543, 478

Offset

1,2

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Formula

a(n) = 2^(2n-2) mod A000040(2n).

Example

a(20)=89 because (2^(2*20-2) mod prime(2*20))=(274877906944 mod 173)=89.

Maple

A176083 := proc(n) modp(2^(2*n-2) , ithprime(2*n)) ; end proc:

Mathematica

Table[PowerMod[4, n-1, Prime[2*n]], {n, 100}] (* G. C. Greubel, Nov 27 2019 *)

Prog

(Sage) A176083 = lambda n: (2**(2*n-2)) % nth_prime(2*n) # D. S. McNeil, Dec 07 2010
(PARI) vector(100, n, lift(Mod(4, prime(2*n))^(n-1)) ) \\ G. C. Greubel, Nov 27 2019
(Magma) [Modexp(4, n-1, NthPrime(2*n)): n in [1..100]]; // G. C. Greubel, Nov 27 2019

Crossrefs

Cf. A000079, A175803.

Sequence in context: A228949 A048227 A213661 * A092193 A277117 A155910

Adjacent sequences: A176080 A176081 A176082 * A176084 A176085 A176086

Keyword

nonn

Author

Juri-Stepan Gerasimov, Dec 07 2010

Extensions

Corrected and extended by D. S. McNeil, Dec 07 2010

Terms a(50) onward added by G. C. Greubel, Nov 27 2019

Status

approved