%I #6 Oct 16 2024 08:15:37
%S 3,5,7,13,19,29,31,37,43,53,59,61,67,73,79,89,103,109,127,137,139,149,
%T 151,157,163,173,179,181,191,193,199,229,239,241,251,257,263,269,271,
%U 277,283,293,307,313,331,337,347,349,359,373,379,389,419,421,431,433
%N Beginning with 3, increasing primes such that no two adjacent terms are congruent mod 4.
%F a(2n-1)==3 (mod 4) and a(2n)==1 (mod 4).
%t a[1] = 3; a[n_] := a[n] = Block[{k}, k = a[n - 1] + 2; While[ ! PrimeQ[k], k = k + 4]; Return[k];]; Table[a[n], {n, 100}]
%K nonn,easy
%O 1,1
%A _Giovanni Teofilatto_, Jan 13 2005
%E Edited and extended by _Ray Chandler_, Jan 19 2005