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A145986
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Ending prime: n-th prime in the first occurrence of n consecutive primes of the form 4k + 1.
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7
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5, 17, 101, 409, 2633, 11657, 11677, 11681, 11689, 373777, 766373, 3358373, 12205121, 12270281, 12270301, 12270317, 297388097, 297779509, 297779513, 1113443473, 1113443521, 1113443533, 1113443549, 1113443561, 84676453373, 84676453429
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(1)=5 is same as A055623(1) because 5 is a single-digit number.
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REFERENCES
| Enoch Haga, Exploring Primes on Your PC and the Internet, 1994-2007. Pp. 30-31. ISBN 978-1-885794-24-6
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EXAMPLE
| a(2)=17 because this is the 2nd prime in the first run of 2 primes where p == 1 mod 4.
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PROG
| (Other) 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
(PARI) r=0; c=0; forprime(p=2, 4e9, if(p%4==1, if(c++>r, r=c; print1(p", ")), c=0)) \\ Charles R Greathouse IV, Mar 22, 2011
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CROSSREFS
| Cf. A055623, A054624, A145988, A145989, A145990, A145991, A145992, A145993, A145994.
Sequence in context: A139390 A145824 A076516 * A200992 A034821 A158007
Adjacent sequences: A145983 A145984 A145985 * A145987 A145988 A145989
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KEYWORD
| nonn
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AUTHOR
| Enoch Haga (Enokh(AT)comcast.net), Oct 26 2008
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EXTENSIONS
| Entry rewritten, and a(13)-a(26), by Charles R Greathouse IV, Mar 22, 2011
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