%I A074170
%S A074170 1,3,6,2,7,13,20,12,3,13,24,12,1,15,30,46,63,81,100,120,141,163,140,164,
%T A074170 189,215,242,270,299,329,360,392,425,459,494,530,567,605,644,684,725,
%U A074170 767,810,854,899,945,992,1040,1089,1139,1190,1242,1295,1349,1404,1460
%V A074170 1,3,6,2,7,13,20,12,3,13,24,12,-1,-15,-30,-46,-63,-81,-100,-120,-141,-163,
               -140,-164,
%W A074170 -189,-215,-242,-270,-299,-329,-360,-392,-425,-459,-494,-530,-567,-605,
               -644,-684,-725,
%X A074170 -767,-810,-854,-899,-945,-992,-1040,-1089,-1139,-1190,-1242,-1295,-1349,
               -1404,-1460
%N A074170 Start with 1, add the next number if one gets a prime then add the next 
               number else subtract the next...
%C A074170 Note that a(22) = -163 is the last prime generated by this sequence. 
               All subsequent terms are composite and equal (16-n)(n+17)/2.
%F A074170 a(n) = -(n-16)(n+17)/2 for n > 22
%e A074170 a(1) = 1, a(2) = 1+2 =3 is a prime hence a(3) = 3 +3 = 6 which is composite 
               hence a(4) = 6-4 = 2 etc.
%t A074170 a=3; Join[{1, 3}, Table[If[PrimeQ[a], a=a+n, a=a-n], {n, 3, 60}]]
%Y A074170 Cf. A074171.
%Y A074170 Sequence in context: A078783 A125717 A065232 this_sequence A076543 A005132 
               A064388
%Y A074170 Adjacent sequences: A074167 A074168 A074169 this_sequence A074171 A074172 
               A074173
%K A074170 easy,sign
%O A074170 1,2
%A A074170 Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 30 2002
%E A074170 Corrected and extended by Jason Earls (zevi_35711(AT)yahoo.com), Sep 
               01 2002
%E A074170 Corrected by T. D. Noe (noe(AT)sspectra.com), Oct 04 2004