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A145991 Final prime in a run of more than 1 consecutive primes == 1 (mod 4). 5
17, 41, 101, 113, 197, 233, 281, 317, 353, 409, 461, 521, 617, 677, 709, 773, 809, 857, 881, 941, 1013, 1097, 1117, 1217, 1249, 1301, 1381, 1433, 1493, 1553, 1601, 1613, 1657, 1697, 1721, 1741, 1801, 1877, 1901, 1949, 1997, 2081, 2129, 2141, 2161, 2237 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

Enoch Haga, Exploring Primes on Your PC and the Internet, 1994-2007. Pp. 30-31. ISBN 978-1-885794-24-6

LINKS

Table of n, a(n) for n=1..46.

EXAMPLE

a(1)=17 because this sequence includes consecutive runs of any length and this ending term > 1 in a run of 2 (comprising 13 and 17) is 17.

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: A070179 A155072 A243451 * A089637 A139961 A188661

Adjacent sequences:  A145988 A145989 A145990 * A145992 A145993 A145994

KEYWORD

easy,nonn

AUTHOR

Enoch Haga, Oct 26 2008

STATUS

approved

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Last modified January 20 02:42 EST 2018. Contains 297939 sequences.