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 A069609 a(1) = 7; a(n) = smallest number such that the juxtaposition a(1)a(2)...a(n) is a prime. 21
 7, 1, 9, 3, 3, 3, 17, 7, 11, 37, 11, 9, 31, 9, 17, 13, 93, 3, 167, 67, 119, 93, 31, 33, 143, 99, 297, 91, 69, 83, 1, 33, 23, 27, 199, 333, 123, 549, 17, 67, 141, 33, 39, 167, 21, 217, 279, 419, 69, 517, 71, 451, 171, 39, 191, 93, 43, 11, 303, 777, 33, 67, 207, 369, 489 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE a(7) = 17 and the number 71933317 is a prime. MATHEMATICA a[1] = 7; a[n_] := a[n] = Block[{k = 1, c = IntegerDigits @ Table[ a[i], {i, n - 1}]}, While[ !PrimeQ[ FromDigits @ Flatten @ Append[c, IntegerDigits[k]]], k += 2]; k]; Table[ a[n], {n, 67}] (from Robert G. Wilson v, Aug 05 2005) CROSSREFS Cf. A069602, A069604, A046257, A074343, A092528, A069603, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A111525. Sequence in context: A019661 A200130 A164003 * A019855 A200288 A117493 Adjacent sequences:  A069606 A069607 A069608 * A069610 A069611 A069612 KEYWORD nonn,base AUTHOR Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 26 2002 EXTENSIONS More terms from Jason Earls (zevi_35711(AT)yahoo.com), Jun 13 2002 STATUS approved

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