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

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, 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, 10, 11, 10, 11, 11, 11, 12, 12, 12, 13, 12, 13, 13, 13, 12, 13, 14, 15, 14, 12, 13, 13, 15, 14

Offset: 1

Author

Reinhard Zumkeller, Apr 14 2008

Keywords

• nonn

Comments

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

Examples

			a(4)=Min{#{3,5,7},#{11,13},#{17,19,23},#{29,31}}=Min{3,2,3,2}=2:
..1 ...3 ...5 ...7 ... primes in first row = {3,5,7},
..9 ..11 ..13 ..15 ... primes in 2nd row = {11,13},
.17 ..19 ..21 ..23 ... primes in 3rd row = {17,19},
.25 ..27 ..29 ..31 ... primes in 4th row = {29,31}.
		

Crossrefs

Cf. A139327, A083382.