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A074340
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a(1) = 5; a(n) is smallest number > a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.
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12
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5, 9, 23, 37, 39, 47, 57, 97, 119, 187, 257, 271, 273, 281, 309, 367, 449, 529, 687, 759, 933, 1031, 1131, 1237, 1263, 1343, 1731, 1861, 2177, 2337, 2589, 2607, 2743, 3191, 3199, 3281, 3499, 3807, 3867, 4133, 6079, 6189, 6593, 7207, 7479, 7523, 8569, 8571
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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a[1] = 5; a[n_] := a[n] = Block[{k = a[n - 1] + 1 + Mod[a[n - 1], 2], c = IntegerDigits @ Table[ a[i], {i, n - 1}]}, While[ !PrimeQ[ FromDigits @ Flatten @ Append[c, IntegerDigits[k]]], k += 2]; k]; Table[ a[n], {n, 48}] (* Robert G. Wilson v *)
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PROG
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(Python)
from sympy import isprime
def aupton(terms):
alst, astr = [5], "5"
while len(alst) < terms:
an = alst[-1] + 2
while an%5 ==0 or not isprime(int(astr + str(an))): an += 2
alst, astr = alst + [an], astr + str(an)
return alst
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CROSSREFS
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Cf. A069606, A046254, A074336, A074338, A074339, A074341, A074342, A074343, A074344, A074345, A074346.
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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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