A138139 Triangle read by rows: row n contains n terms and each column lists the prime numbers A000040.
2, 2, 2, 2, 3, 2, 2, 3, 3, 2, 2, 3, 5, 3, 2, 2, 3, 5, 5, 3, 2, 2, 3, 5, 7, 5, 3, 2, 2, 3, 5, 7, 7, 5, 3, 2, 2, 3, 5, 7, 11, 7, 5, 3, 2, 2, 3, 5, 7, 11, 11, 7, 5, 3, 2, 2, 3, 5, 7, 11, 13, 11, 7, 5, 3, 2, 2, 3, 5, 7, 11, 13, 13, 11, 7, 5, 3, 2, 2, 3, 5, 7, 11
Offset: 1
Examples
Triangle begins:
2
2,2
2,3,2
2,3,3,2
2,3,5,3,2
Links
- Nathaniel Johnston, Table of n, a(n) for n = 1..10000
Programs
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Maple
A138139 := proc(n,k) return ithprime(min(k,n-k+1)): end: seq(seq(A138139(n,k), k=1..n), n=1..13); # Nathaniel Johnston, Apr 30 2011