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A091267 Lengths of runs of 3's in A039702. 4

%I

%S 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,

%T 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,

%U 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

%N Lengths of runs of 3's in A039702.

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

%D 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.

%H T. D. Noe, <a href="/A091267/b091267.txt">Table of n, a(n) for n = 1..10000</a>

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

%e 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.

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

%Y Cf. A002144, A002145, A091318, A039702, A091237.

%K easy,nonn

%O 1,2

%A _Enoch Haga_, Feb 22 2004

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Last modified January 25 19:09 EST 2020. Contains 331249 sequences. (Running on oeis4.)