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A033680 a(1) = 1; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime. 17
1, 1, 3, 11, 13, 29, 39, 49, 83, 141, 247, 273, 291, 347, 373, 401, 441, 567, 571, 651, 903, 957, 1001, 1129, 1401, 1457, 1467, 1561, 1889, 2083, 2169, 2523, 2717, 2743, 3447, 3509, 3711, 4087, 4899, 4983, 5087, 5151, 5263, 5429, 5551, 6017, 7389, 7839 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..800

MATHEMATICA

a[1] = 1; a[n_] := a[n] = Block[{k = a[n - 1], 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 *)

nxt[{c_, a_}]:=Module[{x=a}, While[!PrimeQ[FromDigits[Join[c, IntegerDigits[ x]]]], x+=2]; {Join[c, IntegerDigits[x]], x}]; NestList[nxt, {{1}, 1}, 50][[All, 2]] (* Harvey P. Dale, Sep 14 2018 *)

CROSSREFS

Cf. A074336, A092528, A069602, A033679, A033681, A046254, A046255, A046256, A046257, A046258, A046259, A111524.

Sequence in context: A213697 A287348 A019374 * A032917 A006559 A023248

Adjacent sequences:  A033677 A033678 A033679 * A033681 A033682 A033683

KEYWORD

nonn,nice

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Patrick De Geest, May 15 1998

More terms from Robert G. Wilson v, Aug 05 2005

STATUS

approved

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Last modified July 14 22:58 EDT 2020. Contains 335747 sequences. (Running on oeis4.)