%I A152680
%S A152680 4,12,16,28,36,40,52,60,72,88,96,100,108,112,136,148,156,172,180,192,
%T A152680 196,228,232,240,256,268,276,280,292,312,316,336,348,352,372,388,396,
%U A152680 400,408,420,432,448,456,460,508,520,540,556,568,576,592,600,612,616
%N A152680 a(n)=4*A005098(n)=A002144(n)-1
%C A152680 If we take 4 numbers : 1, A002314(n), A152676(n), A152680(n) then
%C A152680 multiplication table modulo A002144(n) is isomorphc with latin square:
%C A152680 1 2 3 4
%C A152680 2 4 1 3
%C A152680 3 1 4 2
%C A152680 4 3 2 1
%C A152680 and isomorphic with multiplication table of {1,I,-I,-1} where I is Sqrt[ 
               -1],
%C A152680 A152680(n) is isomorphic with -1, A002314(n) with I or -I and A152676(n) 
               vice versa -I or I.
%C A152680 1, A002314(n), A152676(n), A152680(n) are subfield of Galois Field [A002144(n)].
%t A152680 aa = {}; Do[If[Mod[Prime[n], 4] == 1, AppendTo[aa, Prime[n] - 1]], {n, 
               1, 200}]; aa (*Artur Jasinski*)
%Y A152680 A002314, A152676, A152680
%Y A152680 Sequence in context: A090818 A075191 A028594 this_sequence A066632 A038242 
               A048661
%Y A152680 Adjacent sequences: A152677 A152678 A152679 this_sequence A152681 A152682 
               A152683
%K A152680 nonn
%O A152680 1,1
%A A152680 Artur Jasinski (grafix(AT)csl.pl), Dec 10 2008