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A302244 Length of longest run of primes in any of the four diagonals starting from the center of a square number spiral with n at the center.

%I A302244 #10 Jun 25 2018 01:10:34
%S A302244 1,3,0,2,0,3,0,6,0,1,0,5,0,2,0,2,0,8,0,1,0,1,0,4,0,4,0,2,0,3,0,1,0,1,
%T A302244 0,3,0,8,0,1,0,20,0,4,0,1,0,3,0,1,0,1,0,2,0,2,0,2,0,13,0,1,0,2,0,3,0,
%U A302244 7,0,1,0,4,0,1,0,1,0,3,0,1,0,1,0,2,0,2
%N A302244 Length of longest run of primes in any of the four diagonals starting from the center of a square number spiral with n at the center.
%C A302244 As in A299207, the center number is not considered in the run.
%C A302244 Note that a(n)=0 for all even n>0.
%H A302244 Robert Price, <a href="/A302244/b302244.txt">Table of n, a(n) for n = 0..10000</a>
%H A302244 Wikipedia, <a href="https://en.wikipedia.org/wiki/Ulam_spiral">Ulam spiral</a>
%H A302244 <a href="/index/Sp">Index entries for sequences related to spirals</a>
%e A302244 For n=3:
%e A302244 +-------------------------------+
%e A302244 | 39   38  37  36  35   34   33 |
%e A302244 |    +---------------------+    |
%e A302244 | 40 | 19  18  17  16   15 | 32 |
%e A302244 |    |    +-----------+    |    |
%e A302244 | 41 | 20 | 7   6   5 | 14 | 31 |
%e A302244 |    |    |   +---+   |    |    |
%e A302244 | 42 | 21 | 8 | 3   4 | 13 | 30 |
%e A302244 |    |    |   +-------+    |    |
%e A302244 | 43 | 22 | 9  10  11   12 | 29 |
%e A302244 |    |    +----------------+    |
%e A302244 | 44 | 23  24  25  26   27   28 |
%e A302244 |    +--------------------------+
%e A302244 | 45   46  47  48  49   50   51
%e A302244 +--------------------------------
%e A302244 The encountered primes are 7, 19 in the NW direction, 5 in the NE direction and 11 in the SE direction, so a(3) = 2.
%Y A302244 Cf. A215471, A299207.
%K A302244 nonn
%O A302244 0,2
%A A302244 _Robert Price_, Apr 03 2018