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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 (list; graph; refs; listen; history; text; internal format)
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 30-31. ISBN 1-885794-17-7.

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

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Last modified December 14 19:27 EST 2019. Contains 329987 sequences. (Running on oeis4.)