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%I #7 Jul 03 2016 00:17:34
%S 2,2,3,2,2,2,2,2,2,4,3,2,2,3,2,4,2,2,2,3,3,2,2,4,2,2,2,2,2,2,2,2,2,3,
%T 2,2,2,2,2,2,2,2,2,2,2,3,3,3,2,2,2,2,5,2,3,2,2,2,2,2
%N Run lengths of consecutive primes == 1 (mod 4) where the run length is at least 2.
%C The run lengths of 1's in A039702 are 1, 2, 1, 2, 1, 1, 1, 3,.. as listed in A091318. Deleting all 1's from A091318 generates this sequence here. - R. J. mathar, Sep 30 2011
%D Enoch Haga, Exploring Primes on Your PC and the Internet, 1994-2007. Pp. 30-31. ISBN 978-1-885794-24-6
%e a(1)=2 because this sequence includes consecutive runs of any length and this first occurrence > 1 is a run of 2.
%o (UBASIC)
%o 10 'cluster primes
%o 20 C=1
%o 30 input "end #";L
%o 40 for N=3 to L step 2
%o 50 S=int(sqrt(N))
%o 60 for A=3 to S step 2
%o 70 B=N/A
%o 80 if int(B)*A=N then cancel for:goto 170
%o 90 next A
%o 100 C=C+1
%o 110 E=N/4:E=int(E):R=N-(4*E)
%o 120 if R=1 then print N;:C1=C1+1:T1=T1+1:print T1
%o 130 if R=3 then T1=0
%o 140 if R=3 then print " ";N;:C3=C3+1:T2=T2+1:print T2
%o 150 if R=1 then T2=0
%o 160 if T1>10 or T2>10 then stop
%o 170 next
%o 180 print "Total primes=";C;:print "Type A";C1;"Type B";C3
%Y Cf. A055623, A054624, A145986, A145988 - A145994.
%K easy,nonn
%O 1,1
%A _Enoch Haga_, Oct 26 2008
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