A111745 a(2k-1) = k-th prime congruent to 3 mod 4, a(2k) = k-th prime congruent to 1 mod 4.

3, 5, 7, 13, 11, 17, 19, 29, 23, 37, 31, 41, 43, 53, 47, 61, 59, 73, 67, 89, 71, 97, 79, 101, 83, 109, 103, 113, 107, 137, 127, 149, 131, 157, 139, 173, 151, 181, 163, 193, 167, 197, 179, 229, 191, 233, 199, 241, 211, 257, 223, 269, 227, 277, 239, 281, 251, 293, 263

Offset: 1

Author

Jon Perry, Nov 19 2005

Keywords

• nonn

Comments

The graph shows the "race" between the two types of primes. - T. D. Noe, Nov 15 2006

Links

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

Crossrefs

Cf. bisections A002144, A002145.

Programs

Mathematica

Module[{prs=Prime[Range[70]],m3,m1,min},m3=Select[prs,Mod[#,4]==3&];m1=Select[prs,Mod[#,4]==1&];min=Min[Length[m1],Length[m3]];Riffle[ Take[m3,min],Take[m1,min]]] (* Harvey P. Dale, Apr 15 2012 *)

Formula

a(n)=A108546(n+1). [From R. J. Mathar, Aug 15 2008]

Extensions

Edited, corrected and extended by Franklin T. Adams-Watters, Jul 19 2006

Corrected by T. D. Noe, Nov 15 2006