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 A100759 Beginning with 2, least prime not occurring earlier such that the concatenation of first n terms has the least prime factor prime(n). 1
 2, 7, 5, 17, 127, 3, 347, 37, 71, 829, 89, 79, 311, 271, 1103, 823, 827, 7219, 149, 499, 3947, 6367, 2861, 3673, 13781, 2281, 281, 229, 353, 1597, 191, 1879, 2609, 10993, 19961, 4789, 383, 1093, 521, 13681, 9227, 12619, 8219, 12037, 8573, 7621, 6029 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Conjecture: Every prime is a member. LINKS EXAMPLE a(1) = 2, a(2) = 7 and the least prime divisor of 27 is 3. MATHEMATICA a = {2}; b = 2; Do[i = 1; While[Length[Intersection[a, {Prime[i]}]] == 1, i++ ]; While[ !FactorInteger[FromDigits[Join[IntegerDigits[b], IntegerDigits[Prime[i]]]]][[1, 1]] == Prime[n], i++ ]; AppendTo[a, Prime[i]]; b = FromDigits[Join[IntegerDigits[b], IntegerDigits[Prime[i]]]], {n, 2, 30}]; a (* Stefan Steinerberger, Dec 21 2007 *) CROSSREFS Cf. A114025. Sequence in context: A233248 A114025 A135566 * A205448 A180510 A152555 Adjacent sequences:  A100756 A100757 A100758 * A100760 A100761 A100762 KEYWORD base,less,nonn AUTHOR Amarnath Murthy, Nov 23 2004 EXTENSIONS More terms from Stefan Steinerberger, Dec 21 2007 More terms from David Wasserman, Mar 04 2008 STATUS approved

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Last modified June 6 16:34 EDT 2020. Contains 334828 sequences. (Running on oeis4.)