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 A145989 Run lengths of consecutive primes == 1 (mod 4) where the run length is at least 2. 4
 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, 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS 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 REFERENCES Enoch Haga, Exploring Primes on Your PC and the Internet, 1994-2007. Pp. 30-31. ISBN 978-1-885794-24-6 LINKS EXAMPLE a(1)=2 because this sequence includes consecutive runs of any length and this first occurrence > 1 is a run of 2. PROG (UBASIC) 10 'cluster primes 20 C=1 30 input "end #"; L 40 for N=3 to L step 2 50 S=int(sqrt(N)) 60 for A=3 to S step 2 70 B=N/A 80 if int(B)*A=N then cancel for:goto 170 90 next A 100 C=C+1 110 E=N/4:E=int(E):R=N-(4*E) 120 if R=1 then print N; :C1=C1+1:T1=T1+1:print T1 130 if R=3 then T1=0 140 if R=3 then print " "; N; :C3=C3+1:T2=T2+1:print T2 150 if R=1 then T2=0 160 if T1>10 or T2>10 then stop 170 next 180 print "Total primes="; C; :print "Type A"; C1; "Type B"; C3 CROSSREFS Cf. A055623, A054624, A145986, A145988 - A145994. Sequence in context: A340673 A031284 A064569 * A117183 A071187 A329614 Adjacent sequences:  A145986 A145987 A145988 * A145990 A145991 A145992 KEYWORD easy,nonn AUTHOR Enoch Haga, Oct 26 2008 STATUS approved

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Last modified July 29 03:15 EDT 2021. Contains 346340 sequences. (Running on oeis4.)