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A100757
Smallest prime factor of the concatenation of terms of the n-th row of the Stirling's number of the second kind.
1
11, 131, 3, 7, 101, 9066319, 3, 3, 89, 3, 1721, 13, 8761, 1213, 7, 3, 1056688498936034269, 37, 29, 3, 3, 11, 3, 19457, 7, 19, 11, 307, 3, 521, 7, 11887, 3, 3, 7, 3, 13, 11, 103, 43, 22927346902711843, 3, 17, 13, 31, 3, 3, 7, 3, 133811, 37, 11, 13
OFFSET
2,1
COMMENTS
Sequences from other important triangles with unity as the first and the last term can be contributed.
A061113(8) is the first member of A061113 that is not squarefree; it is divisible by 3^3. - David Wasserman, Mar 06 2008
FORMULA
a(n) = A020639[A061113(n)]. - R. J. Mathar, Aug 07 2007
EXAMPLE
a(4) = 3 is the least prime factor of 1761.
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Nov 23 2004
EXTENSIONS
More terms from R. J. Mathar, Aug 07 2007
More terms from David Wasserman, Mar 06 2008
STATUS
approved