

A091267


Lengths of runs of 3's in A039702.


4



1, 2, 2, 1, 2, 1, 2, 2, 2, 2, 1, 1, 2, 1, 1, 4, 1, 1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 2, 7, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 2, 2, 3, 1, 1, 2, 1, 2, 5, 1, 2, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 3, 1, 1, 1, 2, 3, 2, 2, 5, 5, 1, 1, 1, 2, 1, 1, 1, 1, 2, 4, 2, 1, 1, 1, 1, 2, 3, 1, 1, 1, 2, 2, 1, 1, 3, 4, 1
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OFFSET

1,2


COMMENTS

Number of primes congruent to 3 mod 4 in sequence before interruption by a prime 1 mod 4.


REFERENCES

Enoch Haga, Exploring prime numbers on your PC and the Internet with directions to prime number sites on the Internet, 2001, pages 3031. ISBN 1885794177.


LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000


FORMULA

Count primes congruent to 3 mod 4 in sequence before interruption by a prime divided by 4 with remainder 1.


EXAMPLE

a(16)=4 because this is the sequence of primes congruent to 3 mod 4: 199, 211, 223, 227. The next prime is 229, a prime 1 mod 4.


MATHEMATICA

t = Length /@ Split[Table[Mod[Prime[n], 4], {n, 2, 400}]]; Most[Transpose[Partition[t, 2]][[1]]] (* T. D. Noe, Sep 21 2012 *)


CROSSREFS

Cf. A002144, A002145, A091318, A039702, A091237.
Sequence in context: A218775 A191971 A156051 * A003643 A092788 A058062
Adjacent sequences: A091264 A091265 A091266 * A091268 A091269 A091270


KEYWORD

easy,nonn


AUTHOR

Enoch Haga, Feb 22 2004


STATUS

approved



