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A096097
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a(1) = 2, a(2) = 1; for n >= 3, a(n) = least prime not included earlier that divides the concatenation of all previous terms.
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1
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2, 1, 3, 71, 7, 10177, 2100001, 101770000001, 4603, 13, 107, 4013, 23, 3097349301044927552199565217412468305904367, 1847, 37, 367767021959, 54371, 3229, 17, 520063, 29, 389, 8059, 732713, 11, 7123120001, 137, 294563
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Conjecture:(1) Every concatenation is squarefree. (2) This is a rearrangement of the noncomposite numbers other than 5.
Conjecture (1) is false. 3^2 divides the concatenation for a(22) and a(30). [From Sean A. Irvine (sairvin(AT)xtra.co.nz), Nov 25 2009]
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EXAMPLE
| a(4) = 71 as 213 = 3*71.
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CROSSREFS
| Cf. A096098.
Sequence in context: A106485 A126008 A096098 * A016585 A143316 A127192
Adjacent sequences: A096094 A096095 A096096 * A096098 A096099 A096100
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KEYWORD
| base,more,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jun 24 2004
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EXTENSIONS
| More terms from Sean A. Irvine (sairvin(AT)xtra.co.nz), Nov 25 2009
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