

A091318


Lengths of runs of 1's in A039702.


7



1, 2, 1, 2, 1, 1, 1, 3, 2, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 4, 1, 1, 3, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 3, 2, 1, 4, 2, 1, 1, 2, 2, 3, 1, 1, 3, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 4, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 2, 2, 2, 1, 2, 3, 2, 2, 1, 1, 2, 1, 2, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 2, 2, 2, 3, 3, 3
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

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


EXAMPLE

a(8)=3 because this is the sequence of primes congruent to 1 mod 4: 89, 97, 101. The next prime is 103, a prime 3 mod 4.


MATHEMATICA

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


CROSSREFS

Cf. A002144, A002145, A039702, A091267, A091237.
Sequence in context: A175024 A175023 A128115 * A198898 A003639 A174110
Adjacent sequences: A091315 A091316 A091317 * A091319 A091320 A091321


KEYWORD

easy,nonn


AUTHOR

Enoch Haga, Feb 22 2004


STATUS

approved



