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Search: id:A105436
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| A105436 |
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Smallest prime which stays prime when a string of n 1's is appended to it. |
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+0
2
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| 2, 3, 2, 2, 13, 3, 29, 7, 17, 17, 3, 3, 2, 3, 197, 5, 13, 173, 2, 13, 53, 73, 199, 2, 23, 73, 599, 239, 547, 59, 409, 1009, 1277, 19, 3, 383, 137, 13, 653, 103, 139, 227, 19, 127, 359, 193, 1123, 3, 97, 1447, 839, 109, 3, 47, 17, 7, 269, 2, 1657, 1973, 709, 5233, 809
(list; graph; listen)
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OFFSET
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0,1
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EXAMPLE
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a(2)=2 because it is the first prime followed by 3,41,101,107,113,137,... all remaining primes when 11 is appended to each of them.
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MAPLE
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with(numtheory); for n from 1 to 100 do for i from 1 to 5000 do if isprime(ithprime(i)*10^n + sum(10^j, j=0..n-1)) then printf(`%d, `, ithprime(i)); break; fi: od:od: (Sellers)
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MATHEMATICA
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f[n_] := Block[{k = 1, t = Table[1, {n}]}, While[id = IntegerDigits[ Prime[k]]; id[[ -1]] == 1 || !PrimeQ[ FromDigits[ Join[id, t]]], k++ ]; Prime[k]]; Table[ f[n], {n, 0, 62}] (from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 09 2005)
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CROSSREFS
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Cf. A105437, A065821.
Sequence in context: A134142 A138680 A123703 this_sequence A059905 A014836 A085032
Adjacent sequences: A105433 A105434 A105435 this_sequence A105437 A105438 A105439
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KEYWORD
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nonn,base
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AUTHOR
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Lekraj Beedassy (blekraj(AT)yahoo.com), Apr 08 2005
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com) and James A. Sellers (sellersj(AT)math.psu.edu), Apr 09 2005
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