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A139326 Write the first n^2 odd numbers consecutively in n rows of length n: a(n) = minimal number of primes in a row. 3

%I

%S 0,1,2,2,2,2,2,2,2,3,2,4,3,4,4,4,3,3,4,5,4,6,5,5,5,5,5,5,4,5,5,5,6,6,

%T 5,5,5,8,6,7,7,8,7,7,8,8,8,9,9,8,9,9,10,10,9,9,8,9,9,9,10,10,11,9,11,

%U 10,11,10,11,11,11,12,12,12,13,12,13,13,13,12,13,14,15,14,12,13,13,15,14

%N Write the first n^2 odd numbers consecutively in n rows of length n: a(n) = minimal number of primes in a row.

%C a(n) = Min{A139325(n,k): 1<=k<=n}.

%e a(4)=Min{#{3,5,7},#{11,13},#{17,19,23},#{29,31}}=Min{3,2,3,2}=2:

%e ..1 ...3 ...5 ...7 ... primes in first row = {3,5,7},

%e ..9 ..11 ..13 ..15 ... primes in 2nd row = {11,13},

%e .17 ..19 ..21 ..23 ... primes in 3rd row = {17,19},

%e .25 ..27 ..29 ..31 ... primes in 4th row = {29,31}.

%Y Cf. A139327, A083382.

%K nonn

%O 1,3

%A _Reinhard Zumkeller_, Apr 14 2008

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Last modified October 1 06:47 EDT 2022. Contains 357135 sequences. (Running on oeis4.)