A175802 a(n) = 2^(positive nonprime(n)-1) mod (positive nonprime(n+1)).

1, 2, 0, 2, 6, 8, 4, 2, 0, 8, 12, 2, 12, 8, 8, 14, 20, 4, 8, 0, 2, 18, 22, 16, 10, 2, 24, 8, 24, 38, 24, 32, 32, 6, 2, 4, 44, 52, 8, 2, 30, 32, 16, 2, 0, 8, 16, 36, 2, 46, 8, 56, 17, 4, 43, 16, 32, 20, 42, 8, 8, 44, 2, 64, 8, 32, 4, 2, 48, 27, 64, 88, 29, 44

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

a(n) = 2^(A018252(n)-1) mod A018252(n+1).

Example

a(4)=2 because 2^(A018252(4)-1) = 2^7 = 128 mod A018252(4+1) = 10.

Maple

A175802 := proc(n) local n1, n2 ; n1 := A018252(n) ; n2 := A018252(n+1) ; (2^(n1-1)) mod n2 ; end proc: # R. J. Mathar, Dec 05 2010

Mathematica

PowerMod[2, #[[1]]-1, #[[2]]]&/@Partition[Select[Range[150], !PrimeQ[#]&], 2, 1] (* Harvey P. Dale, Sep 26 2025 *)

Crossrefs

Cf. A018252.

Sequence in context: A156815 A303439 A303345 * A161803 A057980 A242840

Adjacent sequences: A175799 A175800 A175801 * A175803 A175804 A175805

Keyword

nonn,less

Author

Juri-Stepan Gerasimov, Dec 04 2010

Extensions

Corrected by R. J. Mathar, Dec 05 2010

Corrected by Harvey P. Dale, Sep 26 2025

Status

approved