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 A105436 Smallest prime that remains prime when a string of n 1's is appended to it. 1
 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; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS EXAMPLE 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. MAPLE 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: # James A. Sellers, Apr 09 2005 MATHEMATICA 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}] (* Robert G. Wilson v, Apr 09 2005 *) CROSSREFS Cf. A065821, A105437. Sequence in context: A138680 A171684 A123703 * A266911 A244075 A354522 Adjacent sequences: A105433 A105434 A105435 * A105437 A105438 A105439 KEYWORD nonn,base AUTHOR Lekraj Beedassy, Apr 08 2005 EXTENSIONS More terms from Robert G. Wilson v and James A. Sellers, Apr 09 2005 STATUS approved

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Last modified April 1 19:13 EDT 2023. Contains 361695 sequences. (Running on oeis4.)