A174620 a(n) = 2^A141468(n) mod prime(n), where A141468(n) is the n-th nonnegative nonprime.

1, 2, 1, 1, 3, 5, 4, 11, 8, 27, 2, 36, 1, 42, 24, 13, 11, 19, 45, 5, 8, 50, 71, 2, 86, 78, 15, 74, 16, 112, 4, 68, 14, 106, 66, 32, 79, 26, 25, 18, 76, 6, 78, 150, 163, 63, 69, 98, 189, 17, 184, 40, 1, 125, 249, 187, 229, 69, 169, 81, 264, 172, 18, 209, 114, 277, 1, 128, 46, 21

Offset: 1

Author

Juri-Stepan Gerasimov, Nov 29 2010

Keywords

• nonn

Examples

			a(14) = 12 because (2^A141468(14) mod prime(14)) = (2097152 mod 43) = 12.
		

Links

• Paolo Xausa, Table of n, a(n) for n = 1..10000

Crossrefs

Main diagonal of A177416.

Cf. A000040, A000079, A141468.

Programs

Mathematica

MapIndexed[PowerMod[2, #, Prime[First[#2]]] &, Join[{0, 1}, Select[Range[100], CompositeQ]]] (* Paolo Xausa, Jul 01 2024 *)

PARI

c=-1; forprime(p=1,999,while(isprime(c++),);print1(lift( Mod(2,p)^c )", ")) \\ M. F. Hasler, Nov 29 2010