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A100757
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Smallest prime factor of the concatenation of terms of the n-th row of the Stirling's number of the second kind.
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1
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,1
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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 (dwasserm(AT)earthlink.net), Mar 06 2008
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FORMULA
| a(n) = A020639[A061113(n)]. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 07 2007
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EXAMPLE
| a(4) = 3 is the least prime factor of 1761.
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CROSSREFS
| Cf. A100755, A100756, A100758, A008277.
Sequence in context: A184280 A157718 A046210 * A099677 A142187 A201484
Adjacent sequences: A100754 A100755 A100756 * A100758 A100759 A100760
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KEYWORD
| base,easy,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Nov 23 2004
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EXTENSIONS
| More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 07 2007
More terms from David Wasserman (dwasserm(AT)earthlink.net), Mar 06 2008
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