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 A236527 Primes obtained by concatenating to the end of previous term the next smallest number that will produce a prime, starting with 3. 1
 3, 31, 311, 3119, 31193, 3119317, 31193171, 311931713, 3119317139, 311931713939, 31193171393933, 3119317139393353, 31193171393933531, 3119317139393353121, 311931713939335312127, 311931713939335312127113, 31193171393933531212711399, 31193171393933531212711399123 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n + 1) is the next smallest prime beginning with a(n). Initial term is 3. These are the primes arising in A069605. LINKS EXAMPLE a(1) = 3 by definition. a(2) is the next smallest prime beginning with 3, so a(2) = 31. a(3) is the next smallest prime beginning with 31, so a(3) = 311. MATHEMATICA A069605[1] = 3; A236527[1] = 3; A069605[n_] := A069605[n] = Block[{k = 1, c = IntegerDigits @ Table[ a[i], {i, n - 1}]}, While[ !PrimeQ[ FromDigits[Flatten[Append[c, IntegerDigits[k]]]]], k += 2]; k]; A236527[n_] := A236527[n] = FromDigits[Flatten[IntegerDigits[A236527[n - 1]], IntegerDigits[A069605[n]]]]; Table[A236527[n], {n, 20}] (* Alonso del Arte, Jan 28 2014 based on Robert G. Wilson v's program for A069605 *) PROG (Python) import sympy from sympy import isprime def b(x): ..num = str(x) ..n = 1 ..while n < 10**3: ....new_num = str(x) + str(n) ....if isprime(int(new_num)): ......print(int(new_num)) ......x = new_num ......n = 1 ....else: ......n += 1 b(3) CROSSREFS Cf. A048553, A110773, A069605. Sequence in context: A100894 A065533 A048550 * A108430 A113075 A111137 Adjacent sequences:  A236524 A236525 A236526 * A236528 A236529 A236530 KEYWORD nonn,base AUTHOR Derek Orr, Jan 27 2014 STATUS approved

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Last modified September 18 18:20 EDT 2019. Contains 327178 sequences. (Running on oeis4.)