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A069608
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a(1) = 6; a(n) = smallest number such that the juxtaposition a(1)a(2)...a(n) is a prime.
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22
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6, 1, 3, 1, 41, 19, 17, 1, 81, 27, 89, 3, 79, 29, 1, 111, 29, 13, 119, 207, 21, 33, 19, 413, 49, 71, 183, 223, 153, 21, 261, 369, 29, 319, 107, 1, 273, 81, 711, 507, 87, 579, 401, 7, 33, 771, 477, 33, 371, 91, 1559, 357, 297, 9, 177, 523, 77, 103, 167, 199, 143, 199
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(5) = 41 and the number 613141 is a prime.
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MATHEMATICA
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a[1] = 6; 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, 63}] (* Robert G. Wilson v, Aug 05 2005 *)
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PROG
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(Python)
from sympy import isprime
def aupton(terms):
alst, astr = [6], "6"
for n in range(2, terms+1):
an = 1
while not isprime(int(astr+str(an))): an += 1
alst, astr = alst + [an], astr + str(an)
return alst
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CROSSREFS
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Cf. A069602, A069604, A046256, A074342, A092528, A069603, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A111525.
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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