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A074365 Smallest prime > the concatenation of the first n natural numbers. 1
2, 13, 127, 1237, 12347, 123457, 1234577, 12345701, 123456791, 12345678923, 1234567891013, 123456789101119, 12345678910111223, 1234567891011121343, 123456789101112131449, 12345678910111213141523, 1234567891011121314151753 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..17.

EXAMPLE

The first prime > 123, the concatenation of the first three natural numbers, is 127. Hence a(3) = 127.

MATHEMATICA

p[n_] := Module[{r, i}, r = 2; i = 1; While[r <= n, i = i + 1; r = Prime[i]]; r]; s = ""; a = {}; Do[s = s <> ToString[Prime[i]]; a = Append[a, p[ToExpression[s]]], {i, 1, 8}]; a

Table[NextPrime[FromDigits[Flatten[IntegerDigits/@Range[n]]]], {n, 20}] (* Harvey P. Dale, Jan 16 2018 *)

CROSSREFS

Sequence in context: A151361 A328008 A073559 * A071362 A108471 A036078

Adjacent sequences:  A074362 A074363 A074364 * A074366 A074367 A074368

KEYWORD

base,nonn

AUTHOR

Joseph L. Pe, Sep 26 2002

EXTENSIONS

More terms from Lior Manor Oct 08 2002

STATUS

approved

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Last modified February 21 02:02 EST 2020. Contains 332086 sequences. (Running on oeis4.)