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 A069608 a(1) = 6; a(n) = smallest number such that the juxtaposition a(1)a(2)...a(n) is a prime. 22
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Michael S. Branicky, Table of n, a(n) for n = 1..303 EXAMPLE a(5) = 41 and the number 613141 is a prime. MATHEMATICA 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 *) PROG (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 print(aupton(62)) # Michael S. Branicky, Jun 01 2021 CROSSREFS Cf. A069602, A069604, A046256, A074342, A092528, A069603, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A111525. Sequence in context: A339387 A074193 A074453 * A211453 A218583 A181166 Adjacent sequences: A069605 A069606 A069607 * A069609 A069610 A069611 KEYWORD nonn,base AUTHOR Amarnath Murthy, Mar 26 2002 EXTENSIONS More terms from Jason Earls, Jun 13 2002 STATUS approved

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Last modified August 7 03:39 EDT 2024. Contains 375008 sequences. (Running on oeis4.)